Modelling regional impacts of climate change on water resources: the Júcar basin,Spain

Abstract

In this paper we analyse all currently available simulated climate scenarios, proposed by the Spanish Agency of Meteorology (AEMET), for the period 2010–2040 on the geographical area covered by the Júcar River basin, located in eastern Spain. This is done through the validation of these scenarios using historical records, and by assessing the impact on water resources for the next 30 years by means of a hydrological model. By taking the period 1960–1990 as the control period, a careful comparison of its historical records against AEMET scenarios is performed. Although temperature records are modelled properly, precipitation data are widely underestimated in a range from 8% to 29%. This wide variability observed in the control period is also found in the precipitation scenarios for the period 2010–2040. The impact on water resources shows a great degree of dispersion, ranging from –13.45% to 18.1% with a mean value of –2.13%.

Editor Z.W. Kundzewicz; Associate editor F. Hattermann     

Simulation and control of the linked systems of water quantity–water quality–socio-economics in the Huaihe River basin

Abstract

This work makes explicit an algebraic expression giving the matrix of transient influence coefficients associated with a one-dimensional semi-confined aquifer model. The domain studied is divided into a series of connected and completely mixed compartments over which the governing equation is discretized. The discrete equations obtained are solved for the compartmental hydraulic head and used to derive the algebraic expression in question. The basic properties of the so-called algebraic influence coefficients are investigated. In particular, their consistency with the exact Green function is highlighted. Finally, the newly derived influence coefficients are applied to a simplified aquifer system in order to formulate and solve the problem of identifying illegal groundwater pumping.     

Seasonal water storage change of the Yangtze River basin detected by GRACE

1 Introduction Large-scale mass redistribution, or temporal varia- tion of mass within the Earth system, the driving force of interactions between solid Earth and geophysical fluids envelope (i.e., atmosphere, ocean, and hydro- sphere), is an important geophysical process critical to human life. Most of the interactions between solid Earth and the atmosphere/oceans happen at seasonal and inter-annual time scales. One important contribu- tor of mass redistribution at seasonal and inter-annual …     

A study of interaction between surface water and groundwater using environmental isotope in Huaisha River basin

The surface water and groundwater are important components of water cycle, and the interaction between surface water and groundwater is the important part in water cycle research. As the effective tracers in water cycle research, environmental isotope and hydrochemistry can reveal the interrelationships between surface water and groundwater effectively. The study area is the Huaisha River basin, which is located in Huairou district, Beijing. The field surveying and sampling for spring, river and well water were finished in 2002 and 2003. The hydrogen and oxygen isotopes and water quality were measured at the laboratory. The spatial characteristics in isotope and evolution of water quality along river lines at the different area were analyzed. The altitude effect of oxygen isotope in springs was revealed, and then using this equation, theory foundation for deducing recharge source of spring was estimated. By applying the mass balance method, the annual mean groundwater recharge rate at the catchment was estimated. Based on the groundwater recharge analysis, combining the hydrogeological condition analysis, and comparing the rainfall-runoff coefficients from the 1960s to 1990s in the Huaisha River basin and those in the Chaobai River basin, part of the runoff in the Huaisha River basin is recharged outside of this basin, in other words, this basin is an un-enclosed basin. On the basis of synthetically analyses, combining the compositions of hydrogen and oxygen isotopes and hydrochemistry, geomorphology, geology, and watershed systems characteristics, the relative contributions between surface water and groundwater flow at the different areas at the catchments were evaluated, and the interaction between surface water and groundwater was re- vealed lastly.     

Spatial–temporal variability in water quality and macro-invertebrate assemblages in the Upper Mara River basin,Kenya

Tropical rivers display profound temporal and spatial heterogeneity in terms of environmental conditions. This aspect needs to be considered when designing a monitoring program for water quality in rivers. Therefore, the physico-chemical composition and the nutrient loading of the Upper Mara River and its two main tributaries, the Amala and Nyangores were monitored. Initial daily, and later a weekly monitoring schedule for 4 months spanning through the wet and dry seasons was adopted. Benthic macro-invertebrates were also collected during the initial sampling to be used as indicators of water quality. The aim of the current study was to investigate the physico-chemical status and biological integrity of the Upper Mara River basin. This was achieved by examining trends in nutrient concentrations and analyzing the structure, diversity and abundance of benthic macro-invertebrates in relation to varying land use patterns. Sampling sites were selected based on catchment land use and the level of human disturbance, and using historical records of previous water quality studies. River water pH, dissolved oxygen, electrical conductivity (EC), temperature, and turbidity were determined in situ. All investigated parameters except iron and manganese had concentration values within allowable limits according to Kenyan and international standards for drinking water. The Amala tributary is more mineralized and also shows higher levels of pH and EC than water from the Nyangores tributary. The latter, however, has a higher variability in both the total phosphorus (TP) and total nitrogen (TN) concentrations. The variability in TP and TN concentrations increases downstream for both tributaries and is more pronounced for TN than for TP. Macro-invertebrate assemblages responded to the changes in land use and water quality in terms of community composition and diversity. The study recommends detailed continuous monitoring of the water quality at shorter time intervals and to identify key macro-invertebrate taxa that can be used to monitor changes of the water quality in rivers of the Mara basin as a result of anthropogenic changes.     

Impact of land-use change on hydrological processes in the Maying River basin, China

Since the 1960s, dramatic changes have taken place in land-use patterns characterized by the persistent expansion of cultivated land and a continuous decrease in natural woodland and grassland in the arid inland river basins of China. It is very important to assess the effects of such land-use changes on the hydrological processes so vital for water resource management and sustainable development on the catchment scale. The Maying River catchment, a typical arid inland watershed located in the middle of the Hexi Corridor in northwest China, was the site chosen to investigate the hydrological responses to land-use changes. The annual runoff, base flow, maximum peak flow, and typical seasonal runoff in both spring and autumn flood periods were selected as the variables in the hydrological processes. Statistical-trend analysis and curvilinear regression were utilized to detect the trends in hydrological variables while eliminating the climatic influence. The relationship between cultivated land-use and hydrological variables was analyzed based on four periods of land-use variation data collected since 1965. A runoff model was established composed of two factors, i.e., cultivated land use and precipitation. The impact of land use changes, especially in the large ar- eas of upstream woodland and grassland turned into cultivated lands since 1967, has resulted in a mean annual runoff decrease of 28.12%, a base flow decline of 35.32%, a drop in the maximum peak discharge of 35.77%, and mean discharge decreases in spring and autumn of 36.05% and 24.87% respectively, of which the contribution of cultivated land expansion to the influence of annual runoff amounts to 77%-80%, with the contribution to the influence of spring discharge being 73%-81%, and that to the influence of base flow reaching 62%-65%. Thus, a rational regulation policy of land use patterns is vitally important to the sustainable use of water resources and the proper development of the entire catchment.     

Hydrological effects of water management measures in the Dovinė River basin,Lithuania

Abstract

Lake ?uvintas, located in southern Lithuania in the Dovin? River basin, is one of the largest lakes and oldest nature reserves in the country. However, changes in the hydrology of the Dovin? River basin, caused by large-scale land reclamation and water management works carried out in the 20th century, have resulted in a significant decrease in the biodiversity of the lake and surrounding wetlands. In order to halt the ongoing deterioration of the lake and wetlands, solutions have to be found at the basin level. Using the SIMGRO model, various measures were therefore analysed to evaluate their impact on the water management in the Dovin? River basin. The results show that it is impossible to fully restore the water dynamics and flow pattern in the Dovin? River to their original state. However, a good measure for improving the hydrological conditions is to block drainage ditches and remove bushes and trees from the wetlands.     

Impact of warming climate on water management for the Ariège River basin (France)

Abstract

The French national project IMAGINE2030 aims to assess future water availability in the Garonne River basin (southwest France) by taking account of changes in both climate and water management in the 2030s. Within this project, two mountainous drainage basins located in the Pyrenees were examined to assess the specific impact of climate change on reservoir management. The Salat River basin at Roquefort, is considered as a proxy (representative of a natural basin), whereas the Ariège River at Foix is influenced by hydropower production in winter and by water releases to sustain low flows in summer. The Cequeau rainfall–runoff model, combined with a simplified model of reservoir management operations, was calibrated on present-day conditions and forced with climate projections derived from the IPCC AR4 report. The results show that a warming climate over the basins induces a decrease in mean annual runoff, a shift to earlier snow melting in mountainous areas and more severe low-flow conditions. The simulations show a decrease in electricity generation. Under two water management scenarios (one “business-as-usual” and the other incorporating an increased downstream water demand in compliance with requirements for increased minimum flow), simulations for the Ariège River basin suggest an earlier filling of the reservoir is necessary in winter to anticipate the increased release from reservoirs in summer to support minimum flow farther downstream.

Editor Z.W. Kundzewicz; Associate editor D. Hughes

Citation Hendrickx, F. and Sauquet, E., 2013. Impact of warming climate on water management for the Ariège River basin (France). Hydrological Sciences Journal, 58 (5), 976–993.     

Do model parameters change under changing climate and land use in the upstream of the Lancang River Basin,China?

ABSTRACT

Hydrological model parameters may vary under the impacts of climate and land-use change. This study proposes a hydrological modelling framework based on the Soil and Water Assessment Tool (SWAT) to investigate the variability of model parameters in three different experiments and to assess the impacts of climate and/or land-use change on these parameters in the upstream of the Lancang River Basin, China. In Experiment 1 (E1), most parameters show clear temporal trends under changing climate and land use, implying that model parameters are strongly influenced by their combined effects. Experiments 2 (E2) and 3 (E3) investigate the separate impacts of land-use change and climate change, respectively. Due to the almost invisible changes in land use in E2, there is no change detected in the model parameters. Temporal trends are found in most parameters in E3 and over half of them show consistent trends with E1, which indicates that climate change has greater impacts on model parameter variability. The simulated extreme streamflow and sediment fluxes vary substantially with time-variant parameters, implying that the variations in model parameters do matter for hydrological prediction.     

Root controls on water redistribution and carbon uptake in the soil–plant system under current and future climate

Understanding photosynthesis and plant water management as a coupled process remains an open scientific problem. Current eco-hydrologic models characteristically describe plant photosynthetic and hydraulic processes through ad hoc empirical parameterizations with no explicit accounting for the main pathways over which carbon and water uptake interact. Here, a soil–plant-atmosphere continuum model is proposed that mechanistically couples photosynthesis and transpiration rates, including the main leaf physiological controls exerted by stomata. The proposed approach links the soil-to-leaf hydraulic transport to stomatal regulation, and closes the coupled photosynthesis–transpiration problem by maximizing leaf carbon gain subject to a water loss constraint. The approach is evaluated against field data from a grass site and is shown to reproduce the main features of soil moisture dynamics and hydraulic redistribution. In particular, it is shown that the differential soil drying produced by diurnal root water uptake drives a significant upward redistribution of moisture both through a conventional Darcian flow and through the root system, consistent with observations. In a numerical soil drying experiment, it is demonstrated that more than 50% of diurnal transpiration is supplied by nocturnal upward water redistribution, and some 12% is provided directly through root hydraulic redistribution. For a prescribed leaf area density, the model is then used to diagnose how elevated atmospheric CO₂ concentration and increased air temperature jointly impact soil moisture, transpiration, photosynthesis, and whole-plant water use efficiency, along with compensatory mechanisms such as hydraulic lift using several canonical forms of root-density distribution.     

Rainfall–runoff–inundation analysis of the 2010 Pakistan flood in the Kabul River basin

Abstract

Pakistan has suffered a devastating flood disaster in 2010. In the Kabul River basin (92 605 km²), large-scale riverine and flash floods caused destructive damage with more than 1100 casualties. This study analysed rainfall–runoff and inundation in the Kabul River basin with a newly developed model that simulates the processes of rainfall–runoff and inundation simultaneously based on two-dimensional diffusion wave equations. The simulation results showed a good agreement with an inundation map produced based on MODIS for large-scale riverine flooding. In addition, the simulation identified flash flood-affected areas, which were confirmed to be severely damaged based on a housing damage distribution map. Since the model is designed to be used even immediately after a disaster, it can be a useful tool for analysing large-scale flooding and to provide supplemental information to agencies for relief operations.

Editor Z.W. Kundzewicz

Citation Sayama, T., Ozawa, G., Kawakami, T., Nabesaka, S. and Fukami, K., 2012. Rainfall–runoff–inundation analysis of the 2010 Pakistan flood in the Kabul River basin. Hydrological Sciences Journal, 57 (2), 298–312.     

Features and trends of the environmental change in the arid areas in Central Asia

RS-monitoring index systems of ecological environment changes at a large scale, based on empirical data and trends in environmental change in Central Asia, are developed using NOAA and MODIS data. Moreover, with the help of mathematical statistics and GIS spatial analysis, the degrees, hazards and distribution extent of various possible ecological problems are discussed, environmental changes in Central Asia in 1990 and 2005 are separately evaluated, and dynamic changes in the environment in Central Asia over a 15-year period are analyzed. The results reveal that during the 15-year period from 1990 to 2005, areas of degenerated vegetation in Kazakhstan, Uzbekistan, Turkmenistan, Kirghizstan and Tadzhikistan were enlarged by 0.069×105 km2, 0.081×105 km2, 0.296×105 km2, 0.022×105 km2 and 0.112×105 km2, respectively. The ecological environment in Central Asia was in the state of significant degeneration and even deterioration. This study proves that NOAA and MODIS data can be used to successfully monitor the environment and provide useful results.     

Variation of snow water resources in northwestern China, 1951–1997

Two models are used to simulate the high-altitude permafrost distribution on the Qinghai-Xizang Plateau. The two models are the “altitude model”, a Gaussian distribution function used to describe the latitudinal zonation of permafrost based on the three-dimensional rules of high-altitude permafrost, and the “frost number model”, a dimensionless ratio defined by manipulation of freezing and thawing degree-day sums. The results show that the “altitude model” can simulate the high-altitude permafrost distribution under present climate conditions accurately. Given the essential hypotheses and using the GCM scenarios from HADCM2, the “altitude model” is used for predicting the permafrost distribution change on the Qinghai-Xizang Plateau. The results show that the permafrost on the plateau will not change significantly during 20–50 a, the percentage of the total disappeared area will not be over 19%. However, by the year 2099, if the air temperature increases by an average of 2.91°C on the plateau, the decrease in the area of permafrost will exceed 58%—almost all the permafrost in the southern plateau and in the eastern plateau will disappear. Project “Fundamental Research of Cryosphere” supported by the Chinese Academy of Sciences.     

Spatial and temporal variations in rainfall erosivity during 1960–2005 in the Yangtze River basin

Water resources and soil erosion are the most important environmental concerns in the Yangtze River basin, where soil erosion and sediment yield are closely related to rainfall erosivity. The present study explores the spatial and temporal changing patterns of the rainfall erosivity in the Yangtze River basin of China during 1960–2005 at annual, seasonal and monthly scales. The Mann–Kendall test is employed to detect the trends during 1960–2005, and the T test is applied to investigate possible changes between 1991–2005 and 1960–1990. Meanwhile the Rescaled Range Analysis is used for exploring future trend of rainfall erosivity. Moreover the continuous wavelet transform technique is using studying the periodicity of the rainfall erosivity. The results show that: (1) The Yangtze River basin is an area characterized by uneven spatial distribution of rainfall erosivity in China, with the annual average rainfall erosivity range from 131.21 to 16842 MJ mm ha^?1 h^?1. (2) Although the directions of trends in annual rainfall erosivity at most stations are upward, only 22 stations have significant trends at the 90 % confidence level, and these stations are mainly located in the Jinshajiang River basin and Boyang Lake basin. Winter and summer are the seasons showing strong upward trends. For the monthly series, significant increasing trends are mainly found during January, June and July. (3) Generally speaking, the results detected by the T test are quite consistent with those detected by the Mann–Kendall test. (4) The rainfall erosivity of Yangtze River basin during winter and summer will maintain a detected significant increasing trend in the near future, which may bring greater risks to soil erosion. (5) The annual and seasonal erosivity of Yangtze River basin all have one significant periodicity of 2–4 years.     

Chemical and isotopic assessment of surface water–shallow groundwater interaction in the arid Grande river basin,North-Central Chile

ABSTRACT

This paper analyses the composition of surface water and shallow groundwater in the Grande River basin, North-Central Chile, using this information to characterize water interactions. Chemical and isotopic data for surface water and groundwater (7 and 6 sampling locations, respectively) were obtained from three sampling campaigns performed in March–April (autumn), August–September (late winter) and December (early summer) 2012. Precipitation samples were also collected. Data was processed using spatial distribution charts, Piper and Stiff diagrams, and multivariate analysis. In general, the results for each method converge on a high degree of connectivity between surface water and shallow groundwater in the study area. Furthermore, approximately a 10% of groundwater contribution to the surface flow discharge was estimated for a particular reach. This multi-method approach was useful for the characterization of surface water–groundwater interactions in the Grande River basin, and may become a suitable and replicable scheme for studies in arid and semi-arid basins facing similar water management challenges.

Editor D. Koutsoyiannis; Associate editor B. Dewals     

Hydro-meteorological drought assessment under climate change impact over the Vu Gia–Thu Bon river basin,Vietnam

Hydro-meteorological drought was assessed with respect to climate change over an estuary catchment Vu Gia-Thu Bon in Central Vietnam, which economy is dependent on agriculture. The fully-distributed hydrological model MIKE SHE was used to simulate river flow over the study region for the period 1991–2010. Drought were assessed using the Standardized Precipitation Index and the Standardized Runoff Index. The future climate was studied using the regional climate model Weather Research and Forecasting by downscaling an ensemble of three global climate models – CCSM3.0, ECHAM5 and MIROC-medium resolution over current (1961–1990) and future climates (2011–2040), under the A2 emissions scenario. The results suggest that, despite hotter and wetter future climate, the area is likely to suffer more from severe and extreme droughts, increasing about 100% in the median range for drought characteristics. Thus, there is a need for proper adaptation and planning for water resources management in this region.     

Is irrigation water price an effective leverage for water management? An empirical study in the middle reaches of the Heihe River basin

Serious water scarcity, low water-use efficiency, and over-exploitation of underground water have hindered socio-economic development and led to environmental degradation in the Heihe River basin, northwestern China. Price leveraging is an important tool in water demand management, and it is considered to be effective in promoting water conservation and improving water use efficiency on the premise that water demand is elastic. In the present study, we examine whether price is an effective and applicable instrument for restraining the increasing demand for agricultural irrigation water in the middle reaches of the Heihe River basin and how will it affect farmers’ decisions on irrigation and crop structure. Specifically, the price elasticity of agricultural water demand was estimated based on the irrigation water demand function. The results show that the agricultural irrigation water price is statistically significant, but its elasticity is very low under current low water price. Price leverage cannot play a significant role in the context of the current pricing regime and farmers’ response to price increase is intrinsically weak. To create incentives for conserving water and improving irrigation efficiency, price mechanism should be accompanied with clearly defined and legally enforceable water rights, restricted water quota measures, and reform of water authorities and water-user associations. Furthermore, increases of surface irrigation water price may lead to the over-withdrawal of groundwater, consequently, effective groundwater licensing and levying must take place to limit the total volume of groundwater withdrawal. In all, improving irrigation efficiency through better management and the adoption of water-saving technologies is the ultimate way to deal with the challenges facing irrigated agriculture in the middle reaches of the Heihe River basin.     

State of heterotrophic bacterioplankton of Yenisei estuary and the zone of Ob–Yenisei discharge in autumn in relation with environmental factors

In September 2011, variations of the total abundance of bacteria were studied, including, for the first time, the abundance of bacteria with intact membranes and active electron transport chains, as well as chlorophyll a concentrations and some hydrological and hydrochemical characteristics of water in Yenisei estuary and the zone of Ob–Yenisei river discharge. The study found abundant, viable, and actively functioning bacterioplankton to exist in the region. The absolute values of all microbiological characteristics were found to decrease with the distance from the freshened waters of Yenisei estuary toward the seawater of the Ob–Yenisei river discharge, while the percentage of bacteria with intact membranes and actively functioning microorganisms in bacterioplankton increased in the same direction. Positive correlations were found to exist between the values of all examined microbiological characteristics and the concentration in water of chlorophyll a, silicium, organic nitrogen, and oxygen, as well as water temperature. The same biological characteristics showed negative correlations with water salinity and phosphates. The spatial distribution of bacteria in the examined water body was supposed to be due mostly to the intensity of hydrodynamic processes, rather than the biogenic matter content of water.     

Spatial and temporal characteristics of changes in precipitation during 1957�C2007 in the Haihe River basin, China

The present study explores the spatial and temporal changing patterns of the precipitation in the Haihe River basin of North China during 1957–2007 at annual, seasonal and monthly scales. The Mann–Kendall and Sen’s T tests are employed to detect the trends, and the segmented regression is applied to investigate possible change points. Meanwhile, Sen’s slope estimator is computed to represent the magnitudes of the temporal trends. The regional precipitation trends are also discussed based on the regional index series of four sub-basins in the basin. Serial correlation of the precipitation series is checked prior to the application of the statistical test to ensure the validity of trend detection. Moreover, moisture flux variations based on the NCEP/NCAR reanalysis dataset are investigated to further reveal the possible causes behind the changes in precipitation. The results show that: (1) Although the directions of annual precipitation trends at all stations are downward, only seven stations have significant trends at the 90% confidence level, and these stations are mainly located in the western and southeastern Haihe River basin. (2) Summer is the only season showing a strong downward trend. For the monthly series, significant decreasing trends are mainly found during July, August and November, while significant increasing trends are mostly observed during May and December. In comparison with the annual series, more intensive changes can be found in the monthly series, which may indicate a shift in the precipitation regime. (3) Most shifts from increasing trends to decreasing trends occurred in May–June, July, August and December series, while opposed shifts mainly occurred in November. Summer is the only season displaying strong shift trends and the change points mostly emerged during the late 1970s to early 1980s. (4) An obvious decrease in moisture flux is observed after 1980 in comparison with the observations before 1980. The results of similar changing patterns between monthly moisture budget and precipitation confirmed that large-scale atmospheric circulation may be responsible for the shift in the annual cycle of precipitation in the Haihe River basin. These findings are expected to contribute to providing more accurate results of regional changing precipitation patterns and understanding the underlying linkages between climate change and alterations of hydrological cycles in the Haihe River basin.