Temporal Distribution Of Water Resources Research Articles

Impacts of climate change on water resources availability in Zambia: implications for irrigation development

The Zambian economy is predominantly based on exploitation of its natural resources. The water resources in particular are important for the socioeconomic development of the country. Managing water resources sustainably requires a good understanding of the current and future availability of these resources at local level: how much water is available, where is it available and when? This study assesses the spatial and temporal distribution of water resources and the impacts of projected climate change on water resource availability in Zambia. The study employs statistical downscaling of future climate scenarios and a water balance model in a hydrological modeling framework to assess the impacts of climate change on water availability. Unlike past studies done at national, regional or global levels, analysis in this study was done at the local river basin level. The main results indicate that temperature is projected to increase by 1.9 °C and 2.3 °C by 2050 and 2100, respectively, in Zambia. Rainfall is projected to decrease by about 3% by mid-century and only marginally by about 0.6% toward the end of the century across the country. These changes in rainfall and temperature will decrease water availability by 13% by the end of the century in 2100 at national level. At the river basin level, the northern basins are projected to stay the same or experience slight gains in water resources compared to those in the southern and western parts of Zambia where reductions up to 9% are projected. In particular, Zambezi, Kafue and Luangwa River basins are projected to have less water resources available due to reduced rainfall and higher temperatures. Two main implications for irrigation development follow in Zambia. More water-efficient irrigation technologies are needed and water resources will need to be better managed and regulated to cope with the projected water stresses due to climate change.

A Review on Applications of Remote Sensing and Geographic Information Systems (GIS) in Water Resources and Flood Risk Management

Water is one of the most critical natural resources that maintain the ecosystem and support people’s daily life. Pressures on water resources and disaster management are rising primarily due to the unequal spatial and temporal distribution of water resources and pollution, and also partially due to our poor knowledge about the distribution of water resources and poor management of their usage. Remote sensing provides critical data for mapping water resources, measuring hydrological fluxes, monitoring drought and flooding inundation, while geographic information systems (GIS) provide the best tools for water resources, drought and flood risk management. This special issue presents the best practices, cutting-edge technologies and applications of remote sensing, GIS and hydrological models for water resource mapping, satellite rainfall measurements, runoff simulation, water body and flood inundation mapping, and risk management. The latest technologies applied include 3D surface model analysis and visualization of glaciers, unmanned aerial vehicle (UAV) video image classification for turfgrass mapping and irrigation planning, ground penetration radar for soil moisture estimation, the Tropical Rainfall Measuring Mission (TRMM) and the Global Precipitation Measurement (GPM) satellite rainfall measurements, storm hyetography analysis, rainfall runoff and urban flooding simulation, and satellite radar and optical image classification for urban water bodies and flooding inundation. The application of those technologies is expected to greatly relieve the pressures on water resources and allow better mitigation of and adaptation to the disastrous impact of droughts and flooding.

Tree cover shows strong sensitivity to precipitation variability across the global tropics

AbstractAimVegetation is sensitive to mean annual precipitation (MAP), but the sensitivity of vegetation to precipitation variability (PV) is less clear. Tropical ecosystems are likely to experience increased PV in the future. Here we assessed the importance, magnitude and mechanism of PV effects on tree cover in the context of covarying environmental drivers such as fire, temperature and soil properties.LocationTropical land.Time period2000–2010.Major taxa studiedTrees.MethodsWe compiled climate, soil and remotely‐sensed tree cover data over tropical land. We then comprehensively assessed the contribution of PV at different time‐scales to tropical tree cover variations and estimated the sensitivity of tree cover to PV changes by conducting rolling‐window regression and variance decomposition analyses. We further adopted a mechanistic modelling approach to test whether water competition between trees and grasses can explain the observed effect of PV.ResultsWe find that PV contributes 33–56% to the total explained spatial variation (65–79%) in tree cover. The contribution of PV depends on MAP and is highest under intermediate MAP (500–1,500 mm). Tree cover generally increases with rainy day frequency and wet season length but shows mixed responses to inter‐annual PV. Based on the estimated sensitivity, tropical tree cover can decrease by 3–5% overall and by up to 20% in Amazonia under a 20% decrease in rainy days. Mechanistic modelling analysis reproduced the continental differences in tree cover along an MAP gradient.Main conclusionsUnder intermediate rainfall regimes (500–1,500 mm), PV can be a more important determinant of tropical tree cover than conventionally proposed drivers such as MAP and fire. The effect of PV likely results from the sensitivity of tree–grass competition to the temporal distribution of water resources. These results show that climate variability can strongly shape the biosphere.

Ecological and Social Vulnerability Issues in the Western Route of South to North Water Transfer Project

Western Route of South to North Water Transfer Project (Western Route Project for short) is a major infrastructure project to solve the uneven spatial and temporal distribution of water resources in West China. The ambitious water transfer project will divert water from China's longest river, the Yangtze River, to Northwest China, where water shortage has become a bottleneck restricting sustainable development. After completion, the project will relieve water shortages in over six provinces in north and Northwest China, affecting about tens of million people. At the same time, it will bring many serious ecological and social problems in the project affected areas.

An innovative method for water resources carrying capacity research – Metabolic theory of regional water resources

The shortage and uneven spatial and temporal distribution of water resources has seriously restricted the sustainable development of regional society and economy. In this study, a metabolic theory for regional water resources was proposed by introducing the biological metabolism concept into the carrying capacity of regional water resources. In the organic metabolic process of water resources, the socio-economic system consumes water resources, while products, services and pollutants, etc. are output. Furthermore, an evaluation index system which takes into the characteristics of the regional water resources, the socio-economic system and the sustainable development principle was established based on the proposed theory. The theory was then applied to a case study to prove its availability. Further, suggestions aiming at improving the regional water carrying capacity were given on the basis of a comprehensive analysis of the current water resources situation.

Reduced streamflow in water-stressed climates consistent with CO2 effects on vegetation

Remotely sensed vegetation and water-balance measurements from 190 river basins across Australia show that sub-humid and semi-arid basins are ‘greening’—as expected under CO2 fertilization—increasing water consumption and reducing streamflow. Global environmental change has implications for the spatial and temporal distribution of water resources, but quantifying its effects remains a challenge. The impact of vegetation responses to increasing atmospheric CO2 concentrations on the hydrologic cycle is particularly poorly constrained1,2,3. Here we combine remotely sensed normalized difference vegetation index (NDVI) data and long-term water-balance evapotranspiration (ET) measurements from 190 unimpaired river basins across Australia during 1982–2010 to show that the precipitation threshold for water limitation of vegetation cover has significantly declined during the past three decades, whereas sub-humid and semi-arid basins are not only ‘greening’ but also consuming more water, leading to significant (24–28%) reductions in streamflow. In contrast, wet and arid basins show nonsignificant changes in NDVI and reductions in ET. These observations are consistent with expected effects of elevated CO2 on vegetation. They suggest that projected future decreases in precipitation4 are likely to be compounded by increased vegetation water use, further reducing streamflow in water-stressed regions.

Evaluating the distribution of water resources in western Canada using synoptic climatology and selected teleconnections. Part 1: winter season

AbstractThe Climatic Redistribution of western Canadian Water Resources project was designed to identify regions of increased/decreased water availability by evaluating a suite of atmospheric, hydroclimatic and streamflow variables. This research component focuses on the atmospheric drivers of air temperature and precipitation in the watersheds originating on the leeward slopes of the Rocky Mountains. Dominant winter (November–April) synoptic‐scale mid‐tropospheric circulation patterns from 1950 to 2011 are classified using self‐organizing maps, and frequency distributions for positive/negative phases of the Southern Oscillation Index (SOI), Pacific Decadal Oscillation (PDO) and Arctic Oscillation are statistically compared. Corresponding high‐resolution gridded temperature and precipitation anomalies are calculated for each synoptic type, and spatial patterns of above/below‐average temperature and precipitation and north/south gradients are identified. Gridded 6‐month values of the Standardized Precipitation–Evapotranspiration Index are also used to categorize winters into regions of high/low snowpack. Results indicate high‐pressure ridges over the Pacific Ocean (western North America), and low‐pressure troughs over western North America (Pacific Ocean) are associated with anomalously cool (warm) and wet (dry) conditions in the study region. Several statistically different synoptic type frequencies were found for positive/negative phases of the SOI, PDO and Arctic Oscillation. Most notably, positive (negative) phases of the SOI and negative (positive) phases of the PDO are associated with a higher (lower) frequency of ridging over the Pacific Ocean (western North America). Through improved knowledge of the relationships between teleconnections, mid‐tropospheric circulation and surface climate, the spatial and temporal distribution of water resources in western Canada is better understood. Copyright © 2014 John Wiley & Sons, Ltd.

An Analysis of Temporal and Spatial Distribution Characteristics of Water Resources in Guangdong Province, China

In view of the difficulty in giving a quantitative description of the degree of uneven distribution of water resources, this paper, based on a cloud model, explores the temporal and spatial distribution characteristics of water resources in some research areas in Guangdong Province by using quantitative methods. The results show that, firstly, cloud images of a cloud model make it possible to describe intuitively the characteristics of the temporal and spatial distribution of water resources and present the differences of these characteristics in different areas through numerical characteristic values. Secondly, there are the least amounts of water resources in western Guangdong and the most in the Pearl River Delta Area. Temporal allocation of water resources is difficult in the northern and eastern parts of this province while spatial allocation difficult in the eastern and western parts. Thirdly, there are more water resources, less non-uniformity in the temporal distribution, greater stability in terms of temporal and spatial distribution but greater non-uniformity in the spatial distribution of water resources in the downstream than upstream of the Pearl River in Guangdong Province. Fourthly, there is less non-uniformity in the spatial distribution than in the temporal distribution in northern Guangdong while stability of spatial distribution is worse than that of the temporal distribution in western Guangdong. In addition, there is less uniformity but greater stability in the spatial distribution than in the temporal distribution of water resources in each research area.

Assessment of water resources availability and demand in the Mara River Basin

A simple model was developed to assess space–time relationships of water resource availability and demand in data limited watersheds. The model used a defined index method to evaluate water resource status with respect to anticipated demands. Input data requirements and data processing steps and strategies were discussed. The model takes outputs from a hydrologic system model and demand estimates and compares supply–demand relationships on the basis of expected percentage of demand satisfaction for the basin of interest. Space–time matrices were used to display results of the model for ease of understanding and decision making. The model was customized and applied for the Mara River Basin (MRB) to assess water resource availability and demand. Assessment of water resources in blocks of water use using indicators of the growing water demand among competing sectors threatening the sustainability of communities and ecosystems in the basin. The spatial and temporal distribution of water resources and the corresponding demand were quantified. Twelve distinct sub-basins were defined in the basin and their water availability was assessed based on long term rainfall-runoff simulation using the Soil and Water Assessment Tool (SWAT). Water demands from six consumptive sectors were divided into three classes and compared with a corresponding three classes of monthly water availability. Results have shown significant variability of water availability and demand in the MRB. Further study on possible quantitative indicators to redistribute water among stakeholders may assist in improving water management.

Feedback mechanisms between water availability and water use in a semi-arid river basin: A spatially explicit multi-agent simulation approach

Understanding the processes responsible for the distribution of water availability over space and time is of great importance to spatial planning in a semi-arid river basin. In this study the usefulness of a multi-agent simulation (MAS) approach for representing these processes is discussed. A MAS model has been developed to represent local water use of farmers that both respond to and modify the spatial and temporal distribution of water resources in a river basin. The MAS approach is tested for the Jaguaribe basin in semi-arid Northeast Brazil. Model validity and required data for representing system dynamics are discussed. For the Jaguaribe basin both positive and negative correlations between water availability and water use have been encountered. It was found that increasing wet season water use in times of drought amplify water stress in the following dry season. It is concluded that with our approach it is possible to validly represent spatial-temporal variability of water availability that is influenced by water use and vice versa.

Estimation de L'équivalent en Eau du Couvert Nival en Montagne Libanaise à Partir des Images RADARSAT-1/Estimation of Water Equivalent of the Snow Cover in Lebanese Mountains by Means of RADARSAT-1 Images

The assessment of the spatial and temporal distribution of water resources in Mediterranean region is crucial for the better management of available resources. In Lebanon in particular, the snow is a crucial parameter for water supply. However, few research works were performed until now to study this potential resource because of difficulties inherent to the measurement of the water volume stored by snow. Remote sensing, and more specifically radar imaging, is the favourite tool for investigating the now water equivalent. This study aims to assess the potential of synthetic aperture radar (SAR) imaging for estimating the snow water equivalent in relation with eight experimental sites distributed over the high plateaus of the Lebanese mountains. With this purpose, an algorithm was tested, which links the backscattering coefficient to physical parameters of the snow and underlying soil, and which allows to assess the water equivalent from the backscattering ratios of a winter scene and a reference scene taken during a period with no snow. To this end, four RADARSAT images were acquired during winter 2001, concurrently to field observations. The model was developed in Quebec for regions with low relief, whereas relief has a decisive influence on the radar signal and on the geometry of images, in a context of high mountains. Consequently, radiometric and geometric corrections were compulsory in order to reduce distortions dues to topographical effects. The preliminary results corroborate the existence of a series of limitations to the application of the algorithm to the particular conditions of the Lebanese snow cover: heterogeneity, accelerated metamorphism and high content of liquid water.

Estimation de L'e?quivalent en Eau du Couvert Nival en Montagne Libanaise a? Partir des Images RADARSAT-1/Estimation of Water Equivalent of the Snow Cover in Lebanese Mountains by Means of RADARSAT-1 Images

Abstract The assessment of the spatial and temporal distribution of water resources in Mediterranean region is crucial for the better management of available resources. In Lebanon in particular, the snow is a crucial parameter for water supply. However, few research works were performed until now to study this potential resource because of difficulties inherent to the measurement of the water volume stored by snow. Remote sensing, and more specifically radar imaging, is the favourite tool for investigating the now water equivalent. This study aims to assess the potential of synthetic aperture radar (SAR) imaging for estimating the snow water equivalent in relation with eight experimental sites distributed over the high plateaus of the Lebanese mountains. With this purpose, an algorithm was tested, which links the backscattering coefficient to physical parameters of the snow and underlying soil, and which allows to assess the water equivalent from the backscattering ratios of a winter scene and a reference scene taken during a period with no snow. To this end, four RADARSAT images were acquired during winter 2001, concurrently to field observations. The model was developed in Quebec for regions with low relief, whereas relief has a decisive influence on the radar signal and on the geometry of images, in a context of high mountains. Consequently, radiometric and geometric corrections were compulsory in order to reduce distortions dues to topographical effects. The preliminary results corroborate the existence of a series of limitations to the application of the algorithm to the particular conditions of the Lebanese snow cover: heterogeneity, accelerated metamorphism and high content of liquid water.