Relating soil phosphorus to dissolved phosphorus in runoff: a single extraction coefficient for water quality modeling

Phosphorus transport from agricultural soils contributes to eutrophication of fresh waters. Computer modeling can help identify agricultural areas with high potential P transport. Most models use a constant extraction coefficient (i.e., the slope of the linear regression between filterable reactive phosphorus [FRP] in runoff and soil P) to predict dissolved P release from soil to runoff, yet it is unclear how variations in soil properties, management practices, or hydrology affect extraction coefficients. We investigated published data from 17 studies that determined extraction coefficients using Mehlich-3 or Bray-1 soil P (mg kg(-1)), water-extractable soil P (mg kg(-1)), or soil P sorption saturation (%) as determined by ammonium oxalate extraction. Studies represented 31 soils with a variety of management conditions. Extraction coefficients from Mehlich-3 or Bray-1 soil P were not significantly different for 26 of 31 soils, with values ranging from 1.2 to 3.0. Extraction coefficients from water-extractable soil P were not significantly different for 17 of 20 soils, with values ranging from 6.0 to 18.3. The relationship between soil P sorption saturation and runoff FRP (microg L(-1)) was the same for all 10 soils investigated, exhibiting a split-line relationship where runoff FRP rapidly increased at P sorption saturation values greater than 12.5%. Overall, a single extraction coefficient (2.0 for Mehlich-3 P data, 11.2 for water-extractable P data, and a split-line relationship for P sorption saturation data) could be used in water quality models to approximate dissolved P release from soil to runoff for the majority of soil, hydrologic, or management conditions. A test for soil P sorption saturation may provide the most universal approximation, but only for noncalcareous soils.     

Traditional pastoralist decision-making processes: lessons for reforms to water resources management in Kenya

The purpose of this paper is to consider the vision for public participation in water resources management embedded in Kenya's 2002 Water Act, as it relates to pastoralists. The Act envisions that responsibility for management of water resources at the local level will be devolved to community-level bodies. Our approach was qualitative and included interviews with government officials and Gabra pastoralists, observation of and participation in traditional Gabra korra meetings and focus group discussions. We conclude that the ‘institutional model’ of participation being pursued through the creation of Water Resource User Associations is particularly problematic for mobile pastoralists such as the Gabra, and we suggest an alternative strategy that would focus on the fostering of deliberation processes.     

Real-time contaminant detection and classification in a drinking water pipe using conventional water quality sensors: Techniques and experimental results

Accurate detection and identification of natural or intentional contamination events in a drinking water pipe is critical to drinking water supply security and health risk management. To use conventional water quality sensors for the purpose, we have explored a real-time event adaptive detection, identification and warning (READiw) methodology and examined it using pilot-scale pipe flow experiments of 11 chemical and biological contaminants each at three concentration levels. The tested contaminants include pesticide and herbicides (aldicarb, glyphosate and dicamba), alkaloids (nicotine and colchicine), E. coli in terrific broth, biological growth media (nutrient broth, terrific broth, tryptic soy broth), and inorganic chemical compounds (mercuric chloride and potassium ferricyanide). First, through adaptive transformation of the sensor outputs, contaminant signals were enhanced and background noise was reduced in time-series plots leading to detection and identification of all simulated contamination events. The improved sensor detection threshold was 0.1% of the background for pH and oxidation–reduction potential (ORP), 0.9% for free chlorine, 1.6% for total chlorine, and 0.9% for chloride. Second, the relative changes calculated from adaptively transformed residual chlorine measurements were quantitatively related to contaminant-chlorine reactivity in drinking water. We have shown that based on these kinetic and chemical differences, the tested contaminants were distinguishable in forensic discrimination diagrams made of adaptively transformed sensor measurements.     

Spatial variability of soil phosphorus in relation to the topographic index and critical source areas: sampling for assessing risk to water quality

A measure of soil P status in agricultural soils is generally required for assisting with prediction of potential P loss from agricultural catchments and assessing risk for water quality. The objectives of this paper are twofold: (i) investigating the soil P status, distribution, and variability, both spatially and with soil depth, of two different first-order catchments; and (ii) determining variation in soil P concentration in relation to catchment topography (quantified as the "topographic index") and critical source areas (CSAs). The soil P measurements showed large spatial variability, not only between fields and land uses, but also within individual fields and in part was thought to be strongly influenced by areas where cattle tended to congregate and areas where manure was most commonly spread. Topographic index alone was not related to the distribution of soil P, and does not seem to provide an adequate indicator for CSAs in the study catchments. However, CSAs may be used in conjunction with soil P data for help in determining a more "effective" catchment soil P status. The difficulties in defining CSAs a priori, particularly for modeling and prediction purposes, however, suggest that other more "integrated" measures of catchment soil P status, such as baseflow P concentrations or streambed sediment P concentrations, might be more useful. Since observed soil P distribution is variable and is also difficult to relate to nationally available soil P data, any assessment of soil P status for determining risk of P loss is uncertain and problematic, given other catchment physicochemical characteristics and the sampling strategy employed.     

Estimating the economic value of improvements in river ecology using choice experiments: an application to the water framework directive

The Water Framework Directive is a major regulatory reform of water resources management within the European Union. Integrated catchment management plans must be prepared for all river basins, in order to achieve 'good ecological status' in all EU waters. Ecological status is a broader measure of water quality than the chemical and biological measures that were previously dominant. The Directive calls for a consideration of the economic costs and benefits of improvements to ecological status. In this paper, we use the choice experiment method to estimate the value of improvements in three components of ecological status. Given the high resource cost of valuation studies, benefits transfer methods will be needed in implementing the Directive. We thus also test the ability of choice experiments for benefits transfer across two very similar rivers in the UK.     

Environmental information sharing: a means to support the legitimization of oyster farmers’ stewardship over water quality management in NSW,Australia

Oyster farmers depend on good water quality. Activities upstream from estuaries result in externalities that impact water quality. Over the last 10 years, oyster farmers have been developing estuary‐wide environmental management systems ( EMSs ) to tackle internal (i.e. industry‐related) and external (i.e. catchment) issues in N ew S outh W ales, A ustralia. Drawing on interview‐based research and document analyses, this paper shows that the process of creating an EMS for the oyster industry, as well as the creation of the EMS itself, resulted in legitimizing the industry's stewardship over the natural resource it depends on (water). For the oyster industry, this result was due to a change in the scale on which EMSs have been developed: instead of viewing issues at the individual business level, the systems expanded their viewpoint to the entire catchment, and included every oyster business in the estuary, as well as all other activities in the upper catchment. By providing a means of communicating internal efforts and with the support of local government bodies, EMSs provided a mechanism with which influence over upstream actors and activities could be exerted. We demonstrate this by using the ‘social‐ecological systems’ and ‘ ENCORE ’ frameworks, emphasizing the transitions that allowed for this change of scale to take place.     

Modeling the impact of revegetation on regional water quality: A collective approach to manage the cumulative impacts of mining in the Bowen Basin,Australia

In this paper we quantify the additional water quality benefits that can be achieved through coordinated cumulative impact management. To do this we simulate coordinated and un-coordinated revegetation investments and compare their impact on achieving regional water quality goals. Our results show that coordination between multiple mining companies achieves additional benefits since prioritization is enabled across a broader range of investment opportunities. Additionally, when coordinated investment is permitted beyond the boundaries of coal mining leases, results show that additional benefits are greatly enhanced since these regions provide more rewarding investment opportunities. Results illustrate (a) how regional coordination may influence reputational benefits of investments, and (b) that coordination is beneficial when investment opportunities are unevenly distributed across the landscape. When additional benefits are achievable, we suggest that mining companies should develop collective investment projects with an understanding of how coordination influences project costs. Similarly, investment projects should be developed with an understanding of investment tradeoffs and how these may adversely impact on regional stakeholders and hence industry reputation. The mining industry has significant potential to contribute to regional wellbeing; however, land management policies must be flexible and promote incentives to enable companies to invest beyond compliance.     

Environmental quality and sustainability in the province of Reggio Emilia (Italy): using multi-criteria analysis to assess and compare municipal performance.

Sustainability has become an increasingly significant issue, although practical implementation remains difficult. In Italy, promoting sustainability is particularly problematic at the provincial and municipal level, where the lack of resources and expertise, and the effects of uncoordinated policies make it difficult to achieve minimum requirements to make sustainable policies operational. One essential requirement is knowledge of baseline environmental conditions in each municipality. In the province of Reggio Emilia (Northern Italy) Legambiente, an environmental association, launched an initiative called 'Ecopaese' aimed at gathering data on environmental conditions and stimulating local administrations to implement sustainable policies. To this end, the state of the environment in the 45 municipalities within the province has been monitored using 25 indicators. Their values have been used to rank the municipalities by multiple criteria analysis (MCA). The results of this comparative approach provide information about the level of sustainability attained in the province as a whole as well as in the single municipalities. It is hoped that it will provide the basis for direct action plans at the provincial level by identifying areas for remedial action, as recommended by Agenda 21, the declaration adopted by many countries attending the Rio Summit in 1992.     

Past climate, future perspective: an exploratory analysis using climate proxies and drought risk assessment to inform water resources management and policy in Maine, USA

In recent decades, significant progress has been made toward reconstructing the past climate record based on environmental proxies, such as tree rings and ice core records. However, limited examples of research that utilizes such data for water resources decision-making and policy exist. Here, we use the reconstructed record of Palmer Drought Severity Index (PDSI), dating back to 1138AD to understand the nature of drought occurrence (severity and duration) in the state of Maine. This work is motivated by the need to augment the scientific basis to support the water resources management and the emerging water allocation framework in Maine (Maine Department of Environmental Protection, Chapter 587). Through a joint analysis of the reconstructed PDSI and historical streamflow record for twelve streams in the state of Maine, we find that: (a) the uncertainties around the current definition of natural drought in the Chapter 587 (based on the 20th century instrumental record) can be better understood within the context of the nature and severity of past droughts in this region, and (b) a drought index provides limited information regarding at-site hydrologic variations. To fill this knowledge gap, a drought index-based risk assessment methodology for streams across the state is developed. Based on these results, the opportunities for learning and challenges facing water policies in a changing hydroclimate are discussed.