Modelling the impacts of land-use and drainage density on the water balance of a lowland–floodplain landscape in northeast Germany

This study presents the modelling approach and impact assessment of different strategies for managing wetland water resources and groundwater dynamics of landscapes which are characterised by the hydrological interactions of floodplains and the adjacent lowlands. The assessment of such impacts is based on the analysis of simulation results of complex scenarios of land-use changes and changes of the density of the drainage-network. The method has been applied to the 198 km² Lower Havel River catchment as a typical example of a lowland–floodplain landscape. The model used consists of a coupled soil water and groundwater model, where the latter one is additionally coupled to the surface channel network. Thus, the hydrological processes of the variable saturated soil zone as well as lateral groundwater flow and the interactions between surface water and groundwater are simulated in an integrated manner. The model was validated for several years of significantly different meteorological conditions. The comparison of lateral and vertical water balance components showed the dominance of lateral flow processes and the importance of the interactions between surface water and groundwater for the overall water balance and the hydrological state of that type of landscape.The simulation of land-use change scenarios showed only minor effects of land-use change on the water balance and groundwater recharge. Changes of groundwater recharge were particularly small within the wetland areas being part of the floodplain where interactions between surface water and groundwater are most pronounced. Alterations in vertical groundwater recharge were counter-balanced by the lateral interaction between groundwater and surface water. More significant deviations in groundwater recharge and storage were observed in the more peripheral areas towards the catchment boundaries which are characterised by greater groundwater distance from the surface and less intense of ground water–surface water interactions.However, the simulation results assuming a coarsening of the drainage network density showed the importance of drainage structure and geometry for the water balance: The removal of the artificial draining ditches in the floodplain would result in significant alterations of total groundwater recharge, i.e., less recharge from winter to early summer and an increase of groundwater recharge during summer and autumn. Furthermore the different effects of groundwater recharge alterations on the dynamics of groundwater stages within the wetland areas close to the floodplains compared to the more peripheral areas could be quantified. Finally, it will be discussed that a well-adjusted co-ordination of different management measures is required to reach a sustainable water resources management of such lowland–floodplain landscapes.     

再生水回灌地下水环境安全风险评价技术方法研究

再生水回灌是水资源管理的一条有效途径,也是污水再生利用的重要发展方向。然而,当再生水以农灌、土壤含水层处理（SAT）、河湖入渗和井灌等方式进行地下水回灌时,不可避免的会在回补地下水的过程中造成对地下水环境的污染风险。针对不同回灌方式建立适用于我国的再生水回灌地下水环境安全风险评价技术体系至关重要。借鉴国内外地下水污染风险评价方法,综合分析再生水回灌对地下水产生风险的关键环节,采用层析分析法,从回灌水特征污染物特性、回灌区地下水固有脆弱性以及回灌工程布设方式3个方面,针对地表灌溉、河湖入渗和井灌3种回灌方式,建立了包含污染物浓度水平、分配系数、溶解度、半衰期、半致死剂量、地下水埋深、降雨入渗补给量、地形坡度、土壤介质、包气带介质、含水层介质、含水层厚度、回灌强度、回灌周期、回灌水停留时间以及取水点与回灌点水平距离16个指标在内的风险评价指标体系。在此基础上,结合地下水使用功能,以20个典型再生水回灌场地调研结果和160种再生水回灌地下水污染风险因子物化特性为数据基础,对各指标进行了风险水平的划分,基于聚类分析法,采用各指标风险指数相乘的风险表征方法计算总风险指数,构建了再生水回灌地下水环境安全风险评价技术方法。该方法有效的避免了指标权重计算的主观性,并且能够直观的找出导致风险的主要因素。结果表明：利用建立的风险评价技术方法可将我国再生水回灌地下水环境安全风险划分为3级,风险值〈5为一级,风险值在5-15之间为二级,风险值〉15为三级。在某再生水回灌场地的应用表明,该回灌区地下水环境安全风险为二级,同时得出回灌水特征污染物特性指标是造成该回灌区地下水环境风险的主要因素。     

Ecological effects of density-independent mortality: application to cooling-water withdrawals.

A wide variety of environmental stresses can cause density-independent mortality in species populations. One example is cooling-water withdrawals, which kill or injure many aquatic organisms near power plants and other industrial facilities. In the United States alone, hundreds of facilities withdraw trillions of gallons from inland and coastal waters every year to cool turbines and other manufacturing equipment. A number of detailed, site-specific studies of the effects of such cooling-water withdrawals have been conducted over the last 30 years, but only a few generalizations have been proposed in the peer-reviewed literature. In this paper we use a series of basic theoretical models to investigate the potential effects of density-independent mortality on species populations and ecosystems, with particular focus on the effects of cooling-water withdrawals on fish populations, fisheries, and aquatic communities. Among other results, we show that the effects of cooling-water withdrawals on a species will depend on the magnitude of other co-occurring stressors, environmental variability, the nature of the management regime in the associated fisheries, and the position of the species in the food web. The general models in this paper can provide a starting point for further empirical case studies and some preliminary conceptual guidance for decision makers who must choose between alternative policy options for controlling cooling-water withdrawals.     

Distributed modeling of groundwater recharge at the macroscale

The GROWA model was applied to the entire Federal State of North Rhine-Westphalia (ca. 34,000 km²) using a grid resolution of 100 m. It conceptually combines distributed meteorological data (winter and summer precipitation and potential evapotranspiration) with distributed site parameters (land use, soil properties, slope gradient, slope exposure, mean depth to groundwater) to facilitate the calculation of long-term annual averages of total runoff. In the GROWA model groundwater recharge is expressed as a constant proportion (baseflow indices) of the total runoff. This portion depends on certain characteristics of the investigated area, e.g. the slope gradient, soil and hydrogeological properties as well as the degree of surface sealing.In this paper special emphasis is put on the influence of geology on groundwater recharge. In this respect, a new calibration procedure for the parameterization of geology-related parameters is described. In previous applications of the GROWA model baseflow indices have been identified on the basis of observed mean monthly low-water runoff values (MoMLR). Since the MoMLR-values significantly overestimate groundwater recharge in solid rock regions due to high interflow proportions, a more sophisticated hydrograph separation method has been applied. In this study runoff data from about 125 gauging stations within the Federal State of North Rhine-Westphalia were used to derive baseflow indices. The raster-based simulation was carried out using a grid resolution of 100 m.The accuracy of the calculated groundwater recharge values for the period 1979–1999 was verified on the basis of data from gauging stations. A good agreement between observed runoff values from the sub-catchments and model results was achieved.     

Invertebrate recolonization of fine-grained beneficial use schemes: An example from the southeast coast of England

The disposal of maintenance dredged material constitutes one of the most important problems in coastal zone management. To minimise ecological impacts, a number of ‘beneficial use’ options have developed whereby the material is regarded as a potential resource and used to recharge or recreate intertidal habitats. This paper presents the results of a sampling programme to investigate the macrofaunal recovery rates, and the underlying mechanisms responsible for them, following a beneficial use scheme involving the placement of fine-grained dredged material on a salt marsh in southeast England. Three stations in the recharge area and three reference stations, located within the same salt marsh system, were selected. These stations were sampled prior to recharge (recharge stations only) then 1 week, 3, 6, 12 and 18 months after the recharge. Sediment redox potentials (1, 2 and 4 cm sediment depths) were also measured on each sampling occasion. The results indicated a rapid recolonization of the fauna typical of the surrounding salt marsh channels. All univariate parameters had recovered after 3 months after the recharge. Active post-juvenile immigration is likely to have been the predominant recovery process. Multivariate data analysis revealed that the community structure of the recharge stations, however, did not progress towards those of the reference sites. Natural spatial variability in community structure at the scale of the recharge-reference station distance, and differences in eventual tidal elevations are factors responsible for these differences. The need to carefully assess reference site suitability in monitoring beneficial use schemes is discussed.     

华南滨海小流域降雨入渗对地下水的补给分析

以华南滨海小流域——中山大学滨海水循环试验基地（试验基地）作为研究区,在对该流域地下水和雨水分别进行采样、实验分析的基础上,利用氯量平衡法（CMB）与地下水动态法计算了该流域的降雨入渗补给系数与给水度。研究发现,试验基地地下水主要受降雨补给,地下水埋深在雨季（4—9月）、旱季（10—3月）的变动范围大致为0～1.5 m与0～0.5 m。根据CMB计算结果,补给区、中间区雨季降雨入渗补给系数分别为旱季的1.3～1.6倍和1.3～2.0倍,且补给区大于中间区（M5井除外）。利用地下水动态法计算次降雨入渗补给系数,所得雨季、旱季的均值（7.6%和4.6%）与CMB计算结果（7.7%和5.3%）较为接近。给水度、雨强与入渗补给系数均存在一定的线性关系。将地下水埋深分别与降雨入渗补给量及潜水蒸发量进行多项式拟合对比,发现降雨入渗对地下水的最大入渗补给埋深约为2.3 m,当埋深为3.1 m时,地下水可获得最大净补给量。     

Transport of bacterial cell (E. coli) from different recharge water resources in porous media during simulated artificial groundwater recharge

• The recharge pond dwelling process induced changes in cell properties. • Cell properties and solution chemistry exerted confounding effect on cell transport. • E. coli cells within different recharge water displayed different spreading risks. Commonly used recharge water resources for artificial groundwater recharge (AGR) such as secondary effluent (SE), river water and rainfall, are all oligotrophic, with low ionic strengths and different cationic compositions. The dwelling process in recharge pond imposed physiologic stress on Escherichia coli (E. coli) cells, in all three types of investigated recharge water resources and the cultivation of E. coli under varying recharge water conditions, induced changes in cell properties. During adaptation to the recharge water environment, the zeta potential of cells became more negative, the hydrodynamic diameters, extracellular polymeric substances content and surface hydrophobicity decreased, while the cellular outer membrane protein profiles became more diverse. The mobility of cells altered in accordance with changes in these cell properties. The E. coli cells in rainfall recharge water displayed the highest mobility (least retention), followed by cells in river water and finally SE cells, which had the lowest mobility. Simulated column experiments and quantitative modeling confirmed that the cellular properties, driven by the physiologic state of cells in different recharge water matrices and the solution chemistry, exerted synergistic effects on cell transport behavior. The findings of this study contribute to an improved understanding of E. coli transport in actual AGR scenarios and prediction of spreading risk in different recharge water sources.     

Isotopic and hydrogeochemical evaluation of groundwater at Qusier-Safaga area,eastern desert,Egypt

The groundwater resources of the El-Qusier-Safaga area on the Red Sea coastal zone have still to be utilised fully for social and economic development. In the present study, an inventory of recharge sources and quality of groundwater in different water bearing formations is made to assist in management of these vital resources. From a hydrochemical point of view, the origin of salinity in the five investigated aquifers are mainly dissolution of terrestrial minerals, leaching of soilsvia floods or ion exchanges processes. Stable isotope data clarify the interaction between different aquifers and indicate that the source of recharge is mainly meteoric water originating from palaeowater of the Pleistocene pluvial period, and from local precipitation as well as some marine water. Evaluation of the groundwater quality for domestic, irrigation and industrial purposes is discussed.     

Surface waves and roughness in self-aerated supercritical flow

In high-velocity open channel flows, free-surface aeration is commonly observed. The effects of surface waves on the air–water flow properties are tested herein. The study simulates the air–water flow past a fixed-location phase-detection probe by introducing random fluctuations of the flow depth. The present model yields results that are close to experimental observations in terms of void fraction, bubble count rate and bubble/droplet chord size distributions. The results show that the surface waves have relatively little impact on the void fraction profiles, but that the bubble count rate profiles and the distributions of bubble and chord sizes are affected by the presence of surface waves.     

A model examining hierarchical wetland networks for watershed stormwater management

There is increasing awareness that solutions to degraded quality and excessive quantity of stormwater and resulting impacts on downstream water bodies may require a watershed approach to management rather that the incremental approach that is now common. Examination of low-relief watersheds characteristic of the southeastern coastal plain reveals common hierarchical patterns of surface water convergence that may be emulated in developed watersheds to enhance the efficacy of peak-flow attenuation and pollutant removal. A dynamic systems model was developed to compare stormwater management using a hierarchical network of treatment wetlands with the standard incremental approach wherein treatment systems are designed considering only site-level effluent criteria. The model simulates watershed hydrology, suspended sediment transport and phosphorus removal and transformation. Results indicate that watershed planning of stormwater collection and treatment systems using hierarchical networks can greatly enhance overall effectiveness (annual retention improvements of 31% for flow, 36% for sediment and 27% for phosphorus) with respect to an equal area of uniformly sized wetlands. Further, network proportions can be adjusted to specific runoff characteristics. Distinct roles were observed for each wetland size class: small headwater wetlands effectively removed sediment, medium-sized mid-reach wetlands retained phosphorus, while large wetlands primarily stored and attenuated long-period hydrologic flows.     

Quantifying the sustainability of water use systems: Calculating the balance between network efficiency and resilience

In ecological network theory, network efficiency and resilience are two essential but complementary attributes of the network structure, and a balance between these factors is critical for an ecosystem's long-term sustainability. Our paper introduces this method and related concepts into water use systems to provide a new angle for sustainability quantification. In this paper, we investigate the meanings of network efficiency and resilience in the context of sustainable development of water use systems, and define sustainable systems based on the optimal balance between network efficiency and resilience. With the consideration of complex artificial characteristics of water use, we propose an optimal water use network and quantify its flows. By ascendency calculation, the balanced network structure can be determined. We then use the four sub-basins of China's Haihe River as a case study to illustrate how the optimal network can be constructed and how the optimal balance for each scenario can be calculated. The results show that the optimal balance for the sub-basins has ascendency values ranging from 0.5970 to 0.7161. By analyzing the contribution of each water use activity to network's balance structure, the location of the optimal balance in water use systems can be better understood. This research represents the first attempt to explore the balance between a network structure's efficiency and resilience as a way to quantify the sustainability of water use systems, and builds a foundation for future studies on the assessment, regulation, and management of water resources.     

华南滨海小流域降雨入渗对地下水的补给分析

以华南滨海小流域——中山大学滨海水循环试验基地(试验基地)作为研究区,在对该流域地下水和雨水分别进行采样、实验分析的基础上,利用氯量平衡法(CMB)与地下水动态法计算了该流域的降雨入渗补给系数与给水度。研究发现,试验基地地下水主要受降雨补给,地下水埋深在雨季(4—9月)、旱季(10—3月)的变动范围大致为0～1.5 m与0～0.5 m。根据CMB计算结果,补给区、中间区雨季降雨入渗补给系数分别为旱季的1.3～1.6倍和1.3～2.0倍,且补给区大于中间区(M5井除外)。利用地下水动态法计算次降雨入渗补给系数,所得雨季、旱季的均值(7.6%和4.6%)与CMB计算结果(7.7%和5.3%)较为接近。给水度、雨强与入渗补给系数均存在一定的线性关系。将地下水埋深分别与降雨入渗补给量及潜水蒸发量进行多项式拟合对比,发现降雨入渗对地下水的最大入渗补给埋深约为2.3 m,当埋深为3.1 m时,地下水可获得最大净补给量。     

Observations and analytical modeling of freshwater and rainwater lenses in coastal dune systems

Observations are reported on (i) groundwater recharge rates under various types of vegetation as measured with megalysimeters in the dunes, (ii) freshwater lenses along the Dutch North Sea coast in the early 1900s, and (iii) rainwater lenses that develop on top of laterally migrating, artificially recharged riverwater. Subsequently analytical methods are presented to estimate annual natural groundwater recharge as function of rainfall and vegetation, and to calculate the size, shape and transition zone of freshwater lenses on saline groundwater and rainwater lenses on infiltrated riverwater. An empirical correction factor, based on the hydraulic resistance of an aquitard within the freshwater lens, is proposed to account for the frequently observed reduction of the Ghyben-Herzberg ratio of 40. This factor raises the groundwater table, reduces the depth of the fresh/salt interface and increases the lens formation time. The suite of methods offers a tool box for knowledge based water management of dune systems, by rapidly predicting: (i) more or less autonomous changes due to sealevel rise, climate change and vegetation development; and (ii) the potential (side) effects of interventions. Knowing what happened or will happen to the fresh water lens or a rainwater lens is important, because changes impact on important natural habitat parameters such as salinity, depth to groundwater table, decalcification rate (and thus on pH, Ca/Al, PO₄, NH₄) and nutrient availability, and on drinking water supply. The analytical models are applied to predict effects of sealevel rise, coastal progradation, vegetation changes, and increased temperature of coastal air and river water to be infiltrated.     

Game-theoretical model for the sustainable use of thermal water resources: the case of Ischia volcanic Island (Italy)

Environmental Geochemistry and Health - The Island of Ischia, one of the Italian active volcanoes, is a famous tourist resort for spa treatments. Spas are supplied by withdrawals from groundwaters...     

Evaluating the environmental flows of China's Wolonghu wetland and land use changes using a hydrological model, a water balance model, and remote sensing

Environmental flows are critical to sustaining a variety of plant and animal communities in wetlands. However, evaluation of environmental flows is hampered by the problem of hydrological and ecological data shortage, especially in many developing countries such as China. Based on a hydrological model, a water balance model and remote sensing data, we assessed the environmental flows of China's Wolonghu wetland with limited data. The hydrological model provides input data for the water balance model of the wetland, and the remote sensing data can be used to assess land use changes. Integration of these two models with the remote sensing data revealed both the environmental flows of the Wolonghu wetland and the relationships between these environmental flows and land use changes. The results demonstrate that environmental flows have direct and indirect influences on the wetland ecosystem and should be linked to sustainable wetland management.     

Modelling spatial and temporal variability in a zero-inflated variable: The case of stone pine (Pinus pinea L.) cone production

Modelling masting habit, i.e. the spatial synchronized annual variability in fruit production, is a huge task due to two main circumstances: (1) the identification of main ecological factors controlling fruiting processes, and (2) the common departure of fruit data series from the main basic statistical assumptions of normality and independence. Stone pine (Pinus pinea L.) is one of the main species in the Mediterranean basin that is able to grow under hard limiting conditions (sandy soils and extreme continental climate), and typically defined as a masting species. Considering the high economical value associated with edible nut production, the masting habit of stone pine has been a main concern for the forest management of the species. In the present work we have used annual fruit data series from 740 stone pine trees measured during a 13 years period (1996-2008) in order: (a) to verify our main hypothesis pointing out to the existence of a weather control of the fruiting process in limiting environments, rather than resource depletion or endogenous inherent cycles; (b) to identify those site factors, stand attributes and climate events affecting specific traits involved in fruiting process; and (c) to construct a model for predicting spatial and temporal patterns of variability in stone pine cone production at different spatial extents as region, stand and tree. Given the nature of the data, the model has been formulated as zero-inflated log-normal, incorporating random components to carry out with the observed lack of independence. This model attains efficiencies close to 70-80% in predicting temporal and spatial variability at regional scale. Though efficiencies are reduced according to the spatial extent of the model, it leads to unbiased estimates and efficiencies over 35-50% when predicting annual yields at tree or stand scale, respectively. In this sense, the proposed model is a main tool for facilitating decision making in some management aspects such as the quantification of total amount of cones annually supplied to nut industry, design of cone harvest programs or the optimal application of seedling felling.     

Terrestrial Reserve Networks Do Not Adequately Represent Aquatic Ecosystems

Abstract: Protected areas are a cornerstone of conservation and have been designed largely around terrestrial features. Freshwater species and ecosystems are highly imperiled, but the effectiveness of existing protected areas in representing freshwater features is poorly known. Using the inland waters of Michigan as a test case, we quantified the coverage of four key freshwater features (wetlands, riparian zones, groundwater recharge, rare species) within conservation lands and compared these with representation of terrestrial features. Wetlands were included within protected areas more often than expected by chance, but riparian zones were underrepresented across all (GAP 1–3) protected lands, particularly for headwater streams and large rivers. Nevertheless, within strictly protected lands (GAP 1–2), riparian zones were highly represented because of the contribution of the national Wild and Scenic Rivers Program. Representation of areas of groundwater recharge was generally proportional to area of the reserve network within watersheds, although a recharge hotspot associated with some of Michigan's most valued rivers is almost entirely unprotected. Species representation in protected areas differed significantly among obligate aquatic, wetland, and terrestrial species, with representation generally highest for terrestrial species and lowest for aquatic species. Our results illustrate the need to further evaluate and address the representation of freshwater features within protected areas and the value of broadening gap analysis and other protected‐areas assessments to include key ecosystem processes that are requisite to long‐term conservation of species and ecosystems. We conclude that terrestrially oriented protected‐area networks provide a weak safety net for aquatic features, which means complementary planning and management for both freshwater and terrestrial conservation targets is needed.     

Hydrogeochemical considerations about the origin of groundwater salinization in some coastal plains of Elba Island (Tuscany,Italy)

Several coastal plains of the Elba Island (Marina di Campo, Portoferraio, Schiopparello, Mola, Porto Azzurro and Barbarossa plains) in Tuscany (Italy) were studied to determine the causes of decline in groundwater quality, using major ion chemistry to establish the causes of groundwater salinization. The study demonstrates that salinization of coastal plain alluvial aquifers is not simply linked to seawater intrusion but is also intimately related to inflows from adjacent aquifers. Ionic ratios, correlation graphs and distribution value maps were employed as the means to understand the hydrochemistry of the study areas. The Mg/Cl ratio in particular can be considered a good tracer to distinguish the main salinization processes that control groundwater chemistry. Seawater intrusion only partly determines the chemistry of some groundwaters, which generally belong to a chloride facies where the salinity is derived principally from freshwater–seawater mixing and the participation of cation exchange. Proceeding inland groundwater quality seems to be principally determined by the inflow of Mg, Ca-HCO₃ or Ca, Na-HCO₃ waters formed from the weathering of silicate minerals in adjoining aquifers. Hydrolysis of these minerals is of prime importance in controlling groundwater chemistry in adjacent alluvial plains. The lateral recharge flows introduce water with a different chemical composition and this variable of freshwater recharge changes the hydrochemistry as a result of mixing between two or more waters types. This situation is further complicated when seawater and base exchange reactions participate, due to seawater intrusion.     

Graphical evaluation of environmental management options: Examples from a forest-insect pest system

A graphical technique is demonstrated which, when combined with any resource simulation model, permits the resource manager to explore the effects of different management options. Also, this technique (nomogram or response surface) permits derivation of “optimal solutions” given particular objectives. Examples of the methodology are given for the spruce budworm—forest system in eastern Canada. Effects of several kinds of uncertainties are dicussed, including uncertainties in model assumptions, management precision, future objectives and system evolution. The graphical nature of nomograms helps managers and analysts to grasp more easily the complicated behavior of ecological systems models. Finally, the role of computer models in decision-making is discussed.     

Control theory applied to natural and environmental resources an exposition

Four control theory models of natural and environmental resource use, drawn from the existing literature, are developed in a manner to emphasize their technical and decentralized interpretive similarity. Renewable, nonrenewable, and amenity resource use are treated as closely related problems of optimal (biological, earth material, ecological, or environmental) capital allocation over time. Thus nonrenewable resources, and the problem of exhaustion, are just limiting (zero growth) cases of renewable resources, and the problem of species extinction. Just as exhaustion can be optimal, extinction can be optimal. Waste recycling is treated as part of the problem of optimal regeneration of “sclean” environmental capital; wilderness use as a problem of managing the regeneration of ecological capital.