Changes in the area of inland lakes in arid regions of central Asia during the past 30 years

Inland lakes are major surface water resource in arid regions of Central Asia. The area changes in these lakes have been proved to be the results of regional climate changes and recent human activities. This study aimed at investigating the area variations of the nine major lakes in Central Asia over the last 30 years. Firstly, multi-temporal Landsat imagery in 1975, 1990, 1999, and 2007 were used to delineate lake extents automatically based on Normalized Difference Water Index (NDWI) threshold segmentation, then lake area variations were detailed in three decades and the mechanism of these changes was analyzed with meteorological data and hydrological data. The results indicated that the total surface areas of these nine lakes had decreased from 91,402.06 km² to 46,049.23 km² during 1975?C2007, accounting for 49.62% of their original area of 1975. Tail-end lakes in flat areas had shrunk dramatically as they were induced by both climate changes and human impacts, while alpine lakes remained relatively stable due to the small precipitation variations. With different water usage of river outlets, the variations of open lakes were more flexible than those of other two types. According to comprehensive analyses, different types of inland lakes presented different trends of area changes under the background of global warming effects in Central Asia, which showed that the increased human activities had broken the balance of water cycles in this region.     

Comment on “A Reanalysis of Long-Term Surface Air Temperature Trends in New Zealand”

de Freitas et al. (2015) (henceforth dFDB) report a trend of 0.28 °C per century over the period 1909–2009 for New Zealand land surface temperatures, from their reanalysis of a composite of seven long-term records. This is much lower than the warming trend of about 0.9 °C per century reported previously by other researchers and much smaller than trends estimated from independent sea surface temperature data from the surrounding region. We show these differences result primarily from the way inhomogeneities in temperature time series at individual stations due to site or instrument changes are identified and adjusted for in the dFDB paper. The adjustments reported in that paper are based on a method designed by one of us (Salinger), but use only a short (1–2-year) overlap period with comparison stations and consider only inhomogeneities in monthly mean (rather than monthly maximum and minimum) temperatures. This leads to underestimates of the statistical significance of individual temperature discontinuities and hence rejection of many valid adjustments. Since there was a systematic tendency for the seven-station sites to be relocated to colder locations as the early half of the twentieth century progressed, this rejection of valid adjustments produces an artificially low rate of warming. We therefore disagree with the trend calculations in the dFDB paper and consider there is no reason to reject the previous estimates of around 0.9 °C warming per century.     

Assessment of regional climatic changes in the Eastern Himalayan region: a study using multi-satellite remote sensing data sets

In this study, an attempt has been made to capture the sensitivity of a mountainous region to elevation-dependent warming and the response of a glacier-laden surface to increasing greenhouse gases (GHGs) and aerosol concentration. Some of the changes Sikkim has undergone due to urban sprawl are as follows: an increase of ~0.7?±?0.46 °C temperature in the past 40 years at an altitude of 5.5 km; a 2.21 km²/year rate of loss of glacierised area in the past 33 years; an increase in absorbed longwave radiation (6?±?2.41 W/m²); an increase in heat fluxes (2?±?0.97 W/m²); a decrease in albedo during the last 30 years; an increase in the concentrations of carbon dioxide (4.42 %), methane (0.61 %), ozone (0.67 %) and black carbon column optical depth (7.19 %); a decrease in carbon monoxide (2.61 %) and an increase in aerosol optical depth (19.16 %) during the last decade; a decrease in precipitation, water yield, discharge and groundwater; and an increase in evapotranspiration during 1971–2005. Detection of three climate signals (1976, 1997 and 2005) in the entire analysis is the quantification of the fact that the climate of Sikkim is moving away from its inter-annual variability. An increase in temperature (0.23 °C/decade) at higher altitude (~5.5 km), suppression of precipitation, decreasing water availability and rapid loss of glacierised area are the evidences of the fact that air pollution is playing a significant role in bringing about regional climatic changes in Sikkim. In this study, change detection method has been used for the first time for the estimation of change in a glacierised area of the region.     

Impact of desertification on temperature trends in the Middle East

The intense interest in desertification and climate change has stimulated detailed studies of temperature records in many areas of the world. In this investigation, the temperature records from the Middle East region are analyzed over the period 1950–1990. Results reveal a linear, statistically significant temperature increase of 0.07 °C/decade over the 41-year period. An analysis of spatial controls on these temperature changes reveals a warming effect associated with both overgrazing and the degree of human-induced desertification. The results of this study are consistent with theoretical and empirical studies predicting and demonstrating a warming signal associated with these land surface changes in the world's dryland areas.     

Water quality trends in New Zealand rivers: 1989–2009

Recent assessments of water quality in New Zealand have indicated declining trends, particularly in the 40 % of the country’s area under pasture. The most comprehensive long-term and consistent water quality dataset is the National Rivers Water Quality Network (NRWQN). Since 1989, monthly samples have been collected at 77 NRWQN sites on 35 major river systems that, together, drain about 50 % of New Zealand’s land area. Trend analysis of the NRWQN data shows increasing nutrient concentrations, particularly nitrogen (total nitrogen and nitrate), over 21 years (1989–2009). Total nitrogen and nitrate concentrations were increasing significantly over the first 11 years (1989–2000), but for the more recent 10-year period, only nitrate concentrations continued to increase sharply. Also, the increasing phosphorus trends over the first 11 years (1989–2000) levelled off over the later 10-year period (2000–2009). Conductivity has also increased over the 21 years (1989–2009). Visual clarity has increased over the full time period which may be the positive result of soil conservation measures and riparian fencing. NRWQN data shows that concentrations of nutrients increase, and visual clarity decreases (i.e. water quality declines), with increasing proportions of pastoral land in catchments. As such, the increasing nutrient trends may reflect increasing intensification of pastoral agriculture.     

Spatio-temporal analyses of cropland degradation in the irrigated lowlands of Uzbekistan using remote-sensing and logistic regression modeling

Advancing land degradation in the irrigated areas of Central Asia hinders sustainable development of this predominantly agricultural region. To support decisions on mitigating cropland degradation, this study combines linear trend analysis and spatial logistic regression modeling to expose a land degradation trend in the Khorezm region, Uzbekistan, and to analyze the causes. Time series of the 250-m MODIS NDVI, summed over the growing seasons of 2000–2010, were used to derive areas with an apparent negative vegetation trend; this was interpreted as an indicator of land degradation. About one third (161,000 ha) of the region’s area experienced negative trends of different magnitude. The vegetation decline was particularly evident on the low-fertility lands bordering on the natural sandy desert, suggesting that these areas should be prioritized in mitigation planning. The results of logistic modeling indicate that the spatial pattern of the observed trend is mainly associated with the level of the groundwater table (odds?=?330 %), land-use intensity (odds?=?103 %), low soil quality (odds?=?49 %), slope (odds?=?29 %), and salinity of the groundwater (odds?=?26 %). Areas, threatened by land degradation, were mapped by fitting the estimated model parameters to available data. The elaborated approach, combining remote-sensing and GIS, can form the basis for developing a common tool for monitoring land degradation trends in irrigated croplands of Central Asia.     

Evaluating the effect of rainfall variability on vegetation establishment in a semidesert grassland

Of the operations required for reclamation in arid and semi-arid regions, establishing vegetation entails the most uncertainty due to reliance on unpredictable rainfall for seed germination and seedling establishment. The frequency of successful vegetation establishment was estimated based on a land surface model driven by hourly atmospheric forcing data, 7 years of eddy-flux data, and 31 years of rainfall data at two adjacent sites in southern Arizona, USA. Two scenarios differing in the required imbibition time for successful germination were evaluated—2 or 3 days availability of sufficient surface moisture. Establishment success was assumed to occur if plants could germinate and if the drying front in the soil did not overtake the growth of seminal roots. Based on our results, vegetation establishment could be expected to fail in 32 % of years. In the worst 10-year span, six of ten plantings would have failed. In the best 10-year span, only one of ten was projected to fail. Across all assessments, at most 3 years in a row failed and 6 years in a row were successful. Funding for reclamation seeding must be available to allow reseeding the following year if sufficient amount and timing of rainfall does not occur.     

Trend, abrupt change, and periodicity of streamflow in the mainstream of Yellow River

The Yellow River is the second largest river in China. The annual runoff of which is only about 2 % of China’s total, but contributes to 9 % of China’s GDP and directly supports 12 % of the population. Today, the water shortage in the Yellow River basin has been aggravated due to rapid population growth and global warming. In order to best maximize water resources management, the natural and observed streamflow series from six hydrologic gauging stations (Guide, Lanzhou, Hekou, Sanmenxia, Huayuankou, and Lijin) are obtained, and the linear regression, Mann–Kendall test, and wavelet transform methods were used to detect the characteristic of streamflow variation from 1956 to 2007. The results show that: (1) both the natural streamflow and observed streamflow present a downward trend over the past 52 years, and the trends are intensified downstream; the decreasing rate of observed streamflow is more rapid than that of the natural streamflow; (2) most of the abrupt changes in natural streamflow and observed streamflow appear in the late 1980s to early 1990s through the result of the Mann–Kendall test; and (3) other than the Guide station, the streamflows at the rest of the stations appear to have strongest periodicity of 19–21 years with a 52-year scale. The results of this study imply that less precipitation and warmer climate in the basin are the primary factors that cause this decreasing trend of natural streamflow. Additionally, the rapid ascent of water consumption by human being results in the reduction of observed streamflow further. Furthermore, human activities like reservoir construction, soil and water conservation measures, etc. influence the streamflow as well. It is recommended that the society takes some effective countermeasures to cope with the water shortage.     

Fluorescence spectroscopic characterization of dissolved organic matter fractions in soils in soil aquifer treatment

This work investigated the effect of soil aquifer treatment (SAT) operation on the fluorescence characteristics of dissolved organic matter (DOM) fractions in soils through laboratory-scale soil columns with a 2-year operation. The resin adsorption technique (with XAD-8 and XAD-4 resins) was employed to characterize the dissolved organic matter in soils into five fractions, i.e., hydrophobic acid (HPO-A), hydrophobic neutral (HPO-N), transphilic acid (TPI-A), transphilic neutral (TPI-N), and hydrophilic fraction (HPI). The synchronous fluorescence spectra revealed the presence of soluble microbial byproduct- and humic acid-like components and polycyclic aromatic compounds in DOM in soils, and SAT operation resulted in the enrichment of these fluorescent materials in all DOM fractions in the surface soil (0–12.5 cm). More importantly, the quantitative method of fluorescence regional integration was used in the analysis of excitation–emission matrix (EEM) spectra of DOM fractions in soils. The cumulative EEM volume (Φ _{T, n} ) results showed that SAT operation led to the enrichment of more fluorescent components in HPO-A and TPI-A, as well as the dominance of less fluorescent components in HPO-N, TPI-N, and HPI in the bottom soil (75–150 cm). Total Φ _{T, n} values, which were calculated as $ {\Phi_{{T,n}}} \times {\mathrm{DOC}} $ , suggested an accumulation of fluorescent organic matter in the upper 75 cm of soil as a consequence of SAT operation. The distribution of volumetric fluorescence among five regions (i.e., P _{i, n} ) results revealed that SAT caused the increased content of humic-like fluorophores as well as the decreased content of protein-like fluorophores in both HPO-A and TPI-A in soils.     

Impacts of climate warming on vegetation in Qaidam Area from 1990 to 2003

The observed warming trend in the Qaidam area, an arid basin surrounded by high mountains, has caused land surface dynamics that are detectable using remotely sensed data. In this paper, we detected land-cover changes in the Qaidam Area between 1990 and 2003 in attempt to depict its spatial variability. The land-cover changes were categorized into two trends: degradation and amelioration, and their spatial patterns were examined. Then we estimated the correlation coefficients between growing-season NDVI and several climatic factors with the consideration of duration and lagging effects. The results show that the inter-annual NDVI variations are positively correlated with May to July precipitations, but not significantly correlated with sunshine duration. We observed no obvious trend in precipitation or sunshine duration from 1990 to 2003. Thus, the authors suggest that their slight fluctuations may not be responsible to the decade-scaled land-cover changes. However, our results indicate a good positive relationship between the NDVI trend and climate warming in the ameliorated areas, but a negative one in the degraded areas. By statistical analyses, we found that degradations mainly occurred at the oasis boundaries and at lower elevations in the non-oasis regions where effective soil moisture might have been reduced by the warming-caused increase in evapotranspiration. At higher elevations where thermal condition acts as a major limiting factor, ameliorations were unequivocally detected, which is attributable to the direct facilitation by temperature increases. We suggest that the impacts of the observed climate warming on vegetation are spatially heterogeneous, depending on the combinations of thermal condition and moisture availability.     

Mean Annual Temperature and Total Annual Precipitation Trends at Canadian Biosphere Reserves

This article examines instrumental climate records from a varietyof stations associated with the following Biosphere Reserves across Canada: (i) Waterton Lakes, (ii) Riding Mountain, (iii) Niagara Escarpment, (iv) Long Point, and (v) Kejimkujik (Candidate Biosphere Reserve). Annual series are generated fromdaily temperature and precipitation values. In addition, homogeneous data are used from other stations and regional records to supplement the records from the local biosphere stations. Long term trends are identified over the period of the instrumental record. In general, data from the interval 1900 to 1998 show cooler temperatures in the 1920's, warmingfrom the early 1940's into the early 1950's, cooling into the1970's, and subsequent warming. At many stations, 1998 is the warmest in the instrumental record. Comparisons with the regional data sets show good agreements between the temperatureseries. The 20th century warming is approximately 1.0 °C in the Riding Mountain area and 0.6 °Cin the Long Point, Niagara Escarpment, and Waterton Lakes areas.There has been slight cooling in the Kejimkujik area over the past half century. Precipitation data show increasing trends inthe Kejimkujik, Long Point, Niagara Escarpment, and Waterton Lakes areas with no long term trend in the Riding Mountain area. This work is part of the Canadian Biosphere Reserves Association (CBRA) Climate Change Initiative (CCI), designed to present climate change information to Biosphere Reserve communities to allow local organizations to understand climate change and adapt to potential impacts.     

Frequency Analysis for Precipitation Events and Dry Durations of Virginia

Stormwater Control Measures (SCMs) are widely used to control and treat stormwater runoff pollution. The first step in SCM design is to evaluate the precipitation patterns at a site. SCMs are normally designed using a storm with a specific return period. A robust design process that uses frequency distribution of precipitation and monitoring of performance could improve our understanding of the behavior and limitations of a particular design. This is not the current norm in the design of SCMs. In this research, frequency analyses (FA) of precipitation events was conducted using hourly precipitation data from 1948 to 2010 for eight sites representing the four major physiographic regions of Virginia. The available data were treated using an inverse distance method to eliminate missing gaps before processing into events determined by minimum inter-event times. FA was at each site to develop frequency plots of precipitation and dry duration. FA of the eight locations indicates a range of rainfall depths from 22.9 mm in Bristol to 35.6 mm in Montebello, compared to the nominal “water quality storm” of 25.4 mm (i.e., 1 in.). Similarly, for dry duration, for a 10 % exceedance probability, the range is from 16.8 days in Richmond and Norfolk to 19.5 days in Montebello. Dry duration provides guidance for vegetation selection, which is important for some SCMs. The degree of variability in both parameters argues for consideration of site-specific information in design. FA was also used to provide guidance to improve monitoring programs. Monte Carlo simulations demonstrated that performance monitoring programs applied in different regions would likely encounter more than 30 % of precipitation events less than 6.35 mm, and 10 % over 25.4 mm under various sampling regimes. The percentages of precipitation events encountered in the Coastal Plain and Piedmont regions are not impacted by sampling regimes, however the Blue Ridge Mountains and Valley and Ridge regions are likely impacted. Anticipating event occurrences improves the chances of implementing a successful monitoring program. The use of these results could enhance the performance of SCMs with consideration of local conditions for both monitoring SCMs and their design basis.     

Quantifying the effect of trend,fluctuation, and extreme event of climate change on ecosystem productivity

Climate change comprises three fractions of trend, fluctuation, and extreme event. Assessing the effect of climate change on terrestrial ecosystem requires an understanding of the action mechanism of these fractions, respectively. This study examined 11 years of remotely sensed-derived net primary productivity (NPP) to identify the impacts of the trend and fluctuation of climate change as well as extremely low temperatures caused by a freezing disaster on ecosystem productivity in Hunan province, China. The partial least squares regression model was used to evaluate the contributions of temperature, precipitation, and photosynthetically active radiation (PAR) to NPP variation. A climatic signal decomposition and contribution assessment model was proposed to decompose climate factors into trend and fluctuation components. Then, we quantitatively evaluated the contributions of each component of climatic factors to NPP variation. The results indicated that the total contribution of the temperature, precipitation, and PAR to NPP variation from 2001 to 2011 in Hunan province is 85 %, and individual contributions of the temperature, precipitation, and PAR to NPP variation are 44 % (including 34 % trend contribution and 10 % fluctuation contribution), 5 % (including 4 % trend contribution and 1 % fluctuation contribution), and 36 % (including 30 % trend contribution and 6 % fluctuation contribution), respectively. The contributions of temperature fluctuation-driven NPP were higher in the north and lower in the south, and the contributions of precipitation trend-driven NPP and PAR fluctuation-driven NPP are higher in the west and lower in the east. As an instance of occasionally triggered disturbance in 2008, extremely low temperatures and a freezing disaster produced an abrupt decrease of NPP in forest and grass ecosystems. These results prove that the climatic trend change brought about great impacts on ecosystem productivity and that climatic fluctuations and extreme events can also alter the ecosystem succession process, even resulting in an alternative trajectory. All of these findings could improve our understanding of the impacts of climate change on the provision of ecosystem functions and services and can also provide a basis for policy makers to apply adaptive measures to overcome the unfavorable influence of climate change.     

Fluoride pollution of atmospheric precipitation and its relationship with air circulation and weather patterns (Wielkopolski National Park, Poland)

A 2-year study (2010–2011) of fluorides in atmospheric precipitation in the open area and in throughfall in Wielkopolski National Park (west-central Poland) showed their high concentrations, reaching a maximum value of 2 mg/l under the tree crowns. These high values indicate substantial deposition of up to 52 mg/m²/year. In 2011, over 51 % of open area precipitation was characterized by fluoride concentration higher than 0.10 mg/l, and in throughfall such concentrations were found in more than 86 % of events. In 2010, a strong connection was evident between fluoride and acid-forming ions, and in 2011, a correlation between phosphate and nitrite ions was seen. Analysis of available data on F^? concentrations in the air did not show an unequivocal effect on F^? concentrations in precipitation. To find reasons for and source areas of high fluoride pollution, the cases of extreme fluoride concentration in rainwater were related to atmospheric circulation and weather patterns. Weather conditions on days of extreme pollution were determined by movement of weather fronts over western Poland, or by small cyclonic centers with meteorological fronts. Macroscale air advection over the sampling site originated in the western quadrant (NW, W, and SW), particularly in the middle layers of the troposphere (2,500–5,000 m a.s.l.). Such directions indicate western Poland and Germany as possible sources of the pollution. At the same time in the lower troposphere, air inflow was frequently from the north, showing short distance transport from local emitters, and from the agglomeration of Poznań.     

The range fraction: an applied method to characterize regional groundwater responses to climate inputs

An important component of ongoing water-resource investigations in the eastern Great Basin, USA, has been to ascertain the impact of future predicted climate change on groundwater availability. As a first step in that analysis, it was hypothesized that potentiometric fluctuations at certain wells would reflect annual-scale precipitation variation. Potentiometric behavior at a well depends on local hydrologic conditions, well construction, and human activities, in addition to natural recharge and regional water levels. Moreover, measurement data are limited for many wells. After preliminarily screening, a large body of well and climate station data, short-term potentiometric responses to annual-scale climate inputs, were identified at 18 wells using a simple visualization methodology developed during the study. For water levels displaying multi-annual trends, the signals were measured as deviations from a linear trendline. Groundwater responses lagged precipitation signals by less than 1 year to as much as 3 years, with most wells showing at most a 1- to 2-year delay. Response amplitude was variable and strongly depended on the hydrologic setting of each well.     

Concentrations, distributions and critical level exceedance assessment of SO2, NO2 and O3 in South Africa

South Africa has been identified as a source of industrial pollution that is significant at a global scale. This study was designed to provide quantitative information, by direct measurement, across northeastern South Africa, which includes the highly industrialised Mpumalanga Highveld. The specific aim of the study was to evaluate whether or not acidic atmospheric pollution poses a threat to soils, plants and water bodies of South Africa. To address this aim, a network of 37 passive sampling sites was established to measure monthly mean concentrations of near-surface SO₂, NO₂ and ozone. The area covered extended over the northern and eastern interior of South Africa while avoiding sources of local emissions such as towns, mines and highways. The field campaign was conducted between August 2005 and September 2007. Spatial distributions and temporal trends for these pollutant gases were assessed. Critical levels analysis comparisons were made against applicable air quality standards, guidelines and limits to evaluate the potential for adverse atmospheric pollution impacts on regional environments. The assessment indicates that only in the central source area of the South African industrial Highveld are some levels exceeded. In remote areas, including the sensitive forested regions of the Drakensberg escarpment, pollutant concentrations are below the critical thresholds for environmental damage.     

Groundwater phosphorus in forage-based landscape with cow-calf operation

Forage-based cow-calf operations may have detrimental impacts on the chemical status of groundwater and streams and consequently on the ecological and environmental status of surrounding ecosystems. Assessing and controlling phosphorus (P) inputs are, thus, considered the key to reducing eutrophication and managing ecological integrity. In this paper, we monitored and evaluated P concentrations of groundwater (GW) compared to the concentration of surface water (SW) P in forage-based landscape with managed cow-calf operations for 3 years (2007–2009). Groundwater samples were collected from three landscape locations along the slope gradient (GW1 10–30 % slope, GW2 5–10 % slope, and GW3 0–5 % slope). Surface water samples were collected from the seepage area (SW 0 % slope) located at the bottom of the landscape. Of the total P collected (averaged across year) in the landscape, 62.64 % was observed from the seepage area or SW compared with 37.36 % from GW (GW1?=?8.01 %; GW2?=?10.92 %; GW3?=?18.43 %). Phosphorus in GW ranged from 0.02 to 0.20 mg L^?1 while P concentration in SW ranged from 0.25 to 0.71 mg L^?1. The 3-year average of P in GW of 0.09 mg L^?1 was lower than the recommended goal or the Florida’s numeric nutrients standards (NNS) of 0.12 mg P L^?1. The 3-year average of P concentration in SW of 0.45 mg L^?1 was about fourfold higher than the Florida’s NNS value. Results suggest that cow-calf operation in pasture-based landscape would contribute more P to SW than in the GW. The risk of GW contamination by P from animal agriculture production system is limited, while the solid forms of P subject to loss via soil erosion could be the major water quality risk from P.     

Response of non-point source pollutant loads to climate change in the Shitoukoumen reservoir catchment

The impacts of climate change on streamflow and non-point source pollutant loads in the Shitoukoumen reservoir catchment are predicted by combining a general circulation model (HadCM3) with the Soil and Water Assessment Tool (SWAT) hydrological model. A statistical downscaling model was used to generate future local scenarios of meteorological variables such as temperature and precipitation. Then, the downscaled meteorological variables were used as input to the SWAT hydrological model calibrated and validated with observations, and the corresponding changes of future streamflow and non-point source pollutant loads in Shitoukoumen reservoir catchment were simulated and analyzed. Results show that daily temperature increases in three future periods (2010–2039, 2040–2069, and 2070–2099) relative to a baseline of 1961–1990, and the rate of increase is 0.63°C per decade. Annual precipitation also shows an apparent increase of 11 mm per decade. The calibration and validation results showed that the SWAT model was able to simulate well the streamflow and non-point source pollutant loads, with a coefficient of determination of 0.7 and a Nash–Sutcliffe efficiency of about 0.7 for both the calibration and validation periods. The future climate change has a significant impact on streamflow and non-point source pollutant loads. The annual streamflow shows a fluctuating upward trend from 2010 to 2099, with an increase rate of 1.1 m³ s⁻¹ per decade, and a significant upward trend in summer, with an increase rate of 1.32 m³ s⁻¹ per decade. The increase in summer contributes the most to the increase of annual load compared with other seasons. The annual NH₄⁺-N load into Shitoukoumen reservoir shows a significant downward trend with a decrease rate of 40.6 t per decade. The annual TP load shows an insignificant increasing trend, and its change rate is 3.77 t per decade. The results of this analysis provide a scientific basis for effective support of decision makers and strategies of adaptation to climate change.     

Water quality status and trends in agriculture-dominated headwaters; a national monitoring network for assessing the effectiveness of national and European manure legislation in The Netherlands

Large nutrient losses to groundwater and surface waters are a major drawback of the highly productive agricultural sector in The Netherlands. The resulting high nutrient concentrations in water resources threaten their ecological, industrial, and recreational functions. To mitigate eutrophication problems, legislation on nutrient application in agriculture was enforced in 1986 in The Netherlands. The objective of this study was to evaluate this manure policy by assessing the water quality status and trends in agriculture-dominated headwaters. We used datasets from 5 agricultural test catchments and from 167 existing monitoring locations in agricultural headwaters. Trend analysis for these locations showed a fast reduction of nutrient concentrations after the enforcement of the manure legislation (median slopes of ?0.55 mg/l per decade for total nitrogen (N-tot) and ?0.020 mg/l per decade for total phosphorus (P-tot)). Still, up to 76 % of the selected locations currently do not comply with either the environmental quality standards (EQSs) for nitrogen (N-tot) or phosphorus (P-tot). This indicates that further improvement of agricultural water quality is needed. We observed that weather-related variations in nutrient concentrations strongly influence the compliance testing results, both for individual locations and for the aggregated results at the national scale. Another important finding is that testing compliance for nutrients based on summer average concentrations may underestimate the agricultural impact on ecosystem health. The focus on summer concentrations does not account for the environmental impact of high winter loads from agricultural headwaters towards downstream water bodies.     

Spatiotemporal analysis of the effect of climate change on vegetation health in the Drakensberg Mountain Region of South Africa

The impact of climate change on mountain ecosystems has been in the spotlight for the past three decades. Climate change is generally considered to be a threat to ecosystem health in mountain regions. Vegetation indices can be used to detect shifts in ecosystem phenology and climate change in mountain regions while satellite imagery can play an important role in this process. However, what has remained problematic is determining the extent to which ecosystem phenology is affected by climate change under increasingly warming conditions. In this paper, we use climate and vegetation indices that were derived from satellite data to investigate the link between ecosystem phenology and climate change in the Namahadi Catchment Area of the Drakensberg Mountain Region of South Africa. The time series for climate indices as well as those for gridded precipitation and temperature data were analyzed in order to determine climate shifts, and concomitant changes in vegetation health were assessed in the resultant epochs using vegetation indices. The results indicate that vegetation indices should only be used to assess trends in climate change under relatively pristine conditions, where human influence is limited. This knowledge is important for designing climate change monitoring strategies that are based on ecosystem phenology and vegetation health.