Climate Change and Water Resource Availability: An Impact Assessment for Bombay and Madras,India

ABSTRACT

Global climate change associated with rising atmospheric concentrations of greenhouse gases may alter regional temperature and precipitation patterns. Such changes could threaten the availability of water resources/Or rapidly growing Third World cities, many of which are already experiencing severe water supply deficiencies. This paper investigates the potential impacts of climate change on water resource availability for two Indian cities, Bombay and Madras. The paper begins by discussing future trends for population growth and water demand in each city. Nat, using climate change scenarios based on three general circulation models (GCMs), the paper assesses how climate change may affect water availability in the two urban regions. The assessment is conducted through the use of a monthly dryness index measuring potential evapotranspiration and precipitation. For each region, the dryness index under “normal” climatic conditions is compared with indexes created using GCM scenarios. The results of this assessment indicate that, unless large increases in regional precipitation accompany climate warming, higher rates of evapotranspiration will mean reduced water availability for both cities. The paper concludes by discussing some implications for water management in Third World cities.     

黄土高原北部淤地坝区域土壤水分模拟及水分有效性——以六道沟流域为例

为揭示黄土高原北部淤地坝区域土壤水分变化特征及其有效性,以黄土高原北部六道沟流域的一处淤地坝区域为研究区,基于实测的水文、气象数据,利用Penman公式和Penman-Monteith公式分别推求参考作物的蒸散发以及草地蒸散发,并对水分有效性进行评估;基于非饱和土壤水分运动方程式(Richards formula)构建了一维土壤水分计算模型,并对土壤水分进行模拟。结果表明:计算时段内,研究区的水分有效性参数值受同期表层土壤含水量和蒸散发的影响较大;淤地坝区域的水分有效性参数均值(0.31)比坡面均值(0.17)大;构建的一维土壤水分模型模拟精度较高,实测值与模拟值之间的相关系数以及模型的纳什效率(Nash-Sutcliffe efficiency(NSE))系数在0.90以上。研究结果可为黄土高原北部淤地坝区域蒸散发和土壤水分运动的深入研究提供基础数据和方法上的借鉴。     

Future Scenarios of Surface Water Resources Availability in North African Dams

Climate change may have strong impacts on water resources in developing countries. In North Africa, many dams and reservoirs have been built to secure water availability in the context of a strong inter-annual variability of precipitation. The goal of this study is to evaluate climate change impacts on surface water resources for the largest dams in Algeria, Morocco and Tunisia using high-resolution (12 km) regional climate models (RCM) simulations. To evaluate the atmospheric demand (evapotranspiration), two approaches are compared: The direct use of actual evaporation simulated by the RCMs, or estimation of reference evapotranspiration computed with the Hargreaves-Samani (HAR) equation, relying on air temperature only, and the FAO-Penman Monteith (PM) equation, computed with temperature, wind, radiation and relative humidity. Results showed a strong convergence of the RCM simulations towards increased temperature and a decrease in precipitation, in particular during spring and the western part of North Africa. A decrease in actual evapotranspiration, highly correlated to the decrease in precipitations, is observed throughout the study area. On the opposite, an increase in reference evapotranspiration is observed, with similar changes between HAR and PM equations, indicating that the main driver of change is the temperature increase. Since the catchments are rather water-limited than energy-limited, despite opposite projections for actual and reference evapotranspiration a decrease of water availability is projected for all basins under all scenarios, with a strong east-to-west gradient. The projected decrease is stronger when considering reference evapotranspiration rather than actual evaporation. These pessimistic future projections are an incentive to adapt the current management of surface water resources to future climatic conditions.     

A Water Budget Model for the Yun-Lin Plain,Taiwan

A water budget model is proposed to estimate the infiltration, runoff, evapotranspiration and recharge in vadose zone and apply to a case study. The instantaneous redistribution of infiltrated water is assumed to be uniform and a linear relationship between evapotranspiration and effective saturation is imposed. Infiltration is described by Philip's solution in conjunction with the time compression approximation method during rainfall. Runoff occurred when rainfall rate exceeds soil-infiltrating rate. The soil profile drainage was determined by evapotranspiration and recharge. Cumulative infiltration, runoff, evapotranspiration and recharge are estimated with different climate conditions and different soil hydraulic properties during simulating period. Analysis shows that initial effective saturation affects the estimated results in this water budget model in the short or mid-term simulations while not in long-term simulations. The climatic conditions of Yun-Lin plain area, Taiwan from 1991 to 1997 are used by referring to hydrological and hydrogeological parameters to provide the computational procedures of this study for estimating recharge. Results showed that the amount of annual recharge was affected by the amount of annual rainfall and soil properties.     

A Canadian Approach To Drought Monitoring For Famine Relief in Africa

ABSTRACT

Poor water supply is the dominant issue in African agriculture. A project aimed at reducing the impact of drought onfood supply levels in Africa is described. The result was a computer software package for analysis of monthly rainfall records which can be operated on a desktop computer. Referencing of current weather analysis results against historical expectations was a major part of the system design. Another feature was to combine current records with climate normals to project mid-rainy season growing conditions to post-harvest crop estimates. A simple simulation model is used to relate rainfall records to evapotranspirationpotential to generate crop water use and soil moisture reserve estimates. Initial scale of application was the entire African continent, but a downsized version has been produced for Zambia. Similar versions could be produced for other countries. The overall project proposed a multi-disciplinary approach to monitoring, in which the weather based system described here is only one component. Satellite technology is a key link to this system. Other applications of the system include both training and long-term planning as well as crop marketing support.     

Water Resource Availability in Three Catchments of Swaziland under Expected Climate Change

Abstract

The greenhouse gases (CO₂, CH₄, N₂O, HFCs, PFCs, and SF₆) concentrations in the atmosphere have increased very much since the industrial revolution. The greenhouse gas effect has been projected to cause a global average temperature increase on the order of 1.4 to 5.8°C over the period of 1990 to 2100. The global average annual precipitation is projected to increase during the 21^st century due to the greenhouse effect. The impact of climate change on hydrology and water resources in the three catchments of Swaziland (Komati, Mbuluzi and Ngwavuma) has been evaluated using General Circulation Model results (rainfall, potential evapotranspiration, air temperature etc.) as inputs to a rainfall runoff model. Three General Circulation Models (GCMs) namely: Canadian Climate Change Equilibrium (CCC-EQ); Geophysical Fluid Dynamics Laboratory (GFDL) and United Kingdom Transient Resilient (UKTR) were found appropriate for use to project the temperature and precipitation changes for Swaziland for year 2075. This information was used to generate the temperature, precipitation and potential evapotranspiration values for the three catchments for year 2075 which was input into a calibrated WatBall rainfall runoff model. Simulation results without taking into consideration of water use projections show that there will be high flows during the summer months but low flows during the winter months. Simulation results after taking into consideration of water use projections show a water deficit from June to September in both the Komati, and Ngwavuma catchments and a water deficit from May to September in the Mbuluzi catchment. This means that the environmental water needs and Swaziland's water release obligation in the three catchments to South Africa and Mozambique will not be met during the winter months under expected climate change conditions.     

Social Science Training for Engineers—Experiences from the USA

ABSTRACT

This paper puts the accent on field measurements of the terms of the hydrological cycle, i.e., precipitation, evapotranspiration, run-off and infiltration, in order to evaluate the available water storage in surface reservoirs, in soils, in aquifers for short and long term planning.

Methodological and technological improvements illustrate in this paper not only the difficulties in obtaining reliable field hydrological data but also the fact that the behavioural knowledge of each term of the hydrological cycle is compulsory in order to determine the limits of the socio-economic development which depends upon the quantity of water resources available and in order to prevent eventual irreversible degradation of the environment.

No universal model exists because a model depends not only on the meteorological, hydrological andgeological conditions of the area under study but also on the planner's objectives concerning urban, industrial, navigational, agricultural and/or recreational activities. The studies of water resources are, therefore, in a permanent stage of pre-management. This is due to the fact that they have to be constantly adapted to new management conditions.

This becomes more and more imperative since water resources studies have been, and still are, undertaken too often in order to solve specific and isolated problems arising from short-sighted and/or short term planning and management.     

Simulation supported scenario analysis for water resources planning: a case study in northern Italy.

The work presents the results of a comprehensive modelling study of surface and groundwater resources in the Muzza-Bassa Lodigiana irrigation district, in Northern Italy. It assesses the impact of changes in land use and irrigation water availability on the distribution of crop water consumption in space and time, as well as on the groundwater resources. A distributed, integrated surface water-groundwater simulation system was implemented and applied to the study area. The system is based on the coupling of a conceptual vadose zone model with the groundwater model MODFLOW. To assess the impact of land use and irrigation water availability on water deficit for crops as well as on groundwater system in the area, a number of management scenarios were identified and compared with a base scenario, reflecting the present conditions. Changes in land use may alter significantly both total crop water requirement and aquifer recharge. Water supply is sufficient to meet demand under present conditions and, from the crop water use viewpoint, a reduction of water availability has a positive effect on the overall irrigation system efficiency; however, evapotranspiration deficit increases, concentrated in July and August, when it may be critical for maize crops.     

One View of the Future

Abstract

Floods, droughts, water scarcity, and water contamination are some among many water problems that are present today and will be even more noticeable in the future. In the past, many different tools have been used for simulation and optimization of complex water resources systems in order to provide an improved basis for decision making. The continuing evolution of information technology (hardware and software) creates a good environment for the transition to new tools. Application of the systems approach to water resources planning, management, and operations has been established as one of the most important advances made in the field of water resources engineering. Based on the lessons learned, this contribution provides my personal view on the tools to be used in the future. Two paradigm shifts are discussed. The first one is focusing on the complexity of the water resources domain and the complexity of the modelling tools in an environment characterised by continuous rapid technological development. The second one deals with water-related data availability and natural variability of domain variables in time and space affecting the uncertainty of water resources decision making.     

Irrigation Water Quality Requirements

ABSTRACT

Rational use of salinized water contributes to the saving of water resources, enlargement of irrigated areas and increased volumes of agricultural produce. It is ascertained that there are several distinguishable levels in irrigation water quality requirements, depending on climatic conditions, drainage conditions OF the territory, fertility, texture and properties of soil, and salt resistance of agricultural crops. In cases where irrigation water quality requirements are not adhered to soil fertility deteriorates, thereby reducing the yield and quality of agricultural produce.

Restrictions on irrigation water quality increase with transfer From the desert zone to dry steppe and steppe.

Thus, the source of irrigation water should be assessed from the viewpoint of alkalinization and salinization hazards with respect to crops of different salt resistance in the steppe, dry steppe and desert zones.     

Worldwide Prospects for Hydropower

ABSTRACT

Nigeria had no real water resources development management programme until 1976 when twelve River Basin Development Authorities (RBDA) were established and charged with functions that covered all the facets in the resources development, utilisation and conservation. Her immense natural water resources are evident in annual heavy rainfall, numerous large rivers and great ground water reserves. Many government agencies and mining companies are involved in the resources management of which RBDA play the largest part. Their greatest achievements are in irrigation agriculture. The achievements, however, have been limited by many factors including financial constraints, inadequate trained manpower and dependable data availability. Many Universities and Technical Institutes were established all over the country for manpower training of all cadres and a Water Data Bank is planned as a future source of dependable data. International cooperation with developed countries and expert assistance from United Nations Organisations will minimise the problems and multiply the achievements of the existing management authorities.     

Simple Daily Dynamic Adaptive Operation Rules for WaterResources Optimization

In large metropolitan areas of the world the operation andmanagement programs for water supply reservoirs play adominant role in economic, social and cultural growth anddevelopment. An unprecedented population increase inaddition to intensive migration from rural areas add extrapressure on the available limited natural resources suchas land, air and water. Although there are many optimizationtechniques including simple linear or dynamic programming whichmight also include chance constraints, they are rather sophisticated for layman operators who deal with the real timejoint operation of various reservoirs. Furthermore, these operation programs require data on daily basis on hydrologicvariable such as rainfall, runoff, evaporation and others which might not be available in sufficient amounts. It is, therefore, necessary to develop simple, dynamic and adaptiveoperation rules according to the special set up of thereservoirs for each city water resources. This article providesthe fundamentals of Istanbul city water-supply-reservoir operation rules suitable for the combination of already existing Supervised Control And DataAcquisition (SCADA) unit of the city. The operation rules are developed on daily basis under the worstpossible constraints to appear. The suggested model is namedSimple Adaptive Daily Dynamic Program (SADP which runs on the concept of critical duration with unpredictable rainfall-runoff, evaporation and infiltration properties.     

Estimation of the Water Resources Potential in the Island System of the Aegean Archipelago,Greece

Abstract

The present paper tries to estimate the surface water resources potential in some of the major Aegean islands in an effort to provide a means for the continuous development of the region, and, by extension, for similar areas around the world. The islands have to confront the challenge of surviving in a semiarid environment under the constraints of uneven water resources distribution both in space and time. In addition to these, tourism development, industrialization and highly water consumptive life styles have exacerbated perennial problems in water resources and water resources management. The framework of the present effort has a two-prong emphasis. In the first part, a simulation model is presented, which tries to estimate the potential surface runoff under physical, structural organizational, and institutional constraints. The methodology and the premises of the simulation process are delineated. In the second part, the results of the model's application in distinct cases are demarcated. The final product, namely the model and the resulting runoff coefficients, are presented in the form of a standard, which may provide practitioners in the field as well as decisionmakers the means for an initial reference in pertinent developmental efforts. Finally, the conclusions and recommendations raise the question of ecosystem resilience and point towards the urgent and continuous need for the application of integrated water resources management principles.     

Multicriteria Analysis For Water Productivity in the Jordan Valley

Abstract

Multiple variables associated with agricultural sector, including crop water consumption, salinity tolerance, marketing, evapotranspiration and other factors related to industrial sector, were incorporated into a multi-criteria analysis (MCA). The MCA utilized Analytical Hierarchy Process (AHP) which resulted in the prioritization of water use for management in the Jordan Valley. The inputs to the MCA were generated through metrological variables for the Jordan Valley for the period 1980 to 1999. Soil data and crop data were evaluated using the EVAPOT program, the KCISA program, and the ISAREG model to estimate reference evapotranspiration, crop coefficiency, crop water requirement, and calculations of water productivity for agricultural and industrial sectors. The results of the MCA make recommendations for enhancing long-term sustainability of water resources in the Jordan Valley, while allowing for water utilization and economic growth. The MCA ranked the date palm as the highest priority crop with respect to the goal of sustainable agricultural use of water. Apparel manufacturing was the most sustainable industry. Overall, the industrial sector seems to perform better with regards to water productivity than the agricultural sector. It can be concluded that the MCA tool and ISAREG model are potentially positive contributions to the process of decision- making for selection and ranking of alternatives for help in solving problems that include conflicting criteria.     

Hourly Analyses of Hydrological and Water Quality Simulations Using the ESWAT Model

Detailed analyses of hydrological and water quality variables are very important to study the dynamic processes in a river basin. In this study, we have further modified the Enhanced Soil and Water Assessment Tool (ESWAT) model by incorporating hourly evapotranspiration and overland flow routing modules. Results from comparison of the performances by two ESWAT versions indicate that the modified version performed better than the original model. The modified ESWAT model has reasonably reproduced observed time series runoff and most commonly collected water quality data. In addition, input data availability at required spatial and temporal resolutions is the major bottleneck in implementing many detailed hydrological models. In this paper, we have also developed a robust methodology to successfully disaggregate daily rainfall data into hourly datasets. Furthermore, we have assessed the implications of such daily rainfall disaggregation schemes on subsequent simulation of hydrological and water quality variables at river basin level. The outcomes suggest that the multivariate rainfall disaggregation scheme better reproduced observed rainfall and runoff data.     

An Integrated Assessment of the Impacts of Changing Climate Variability on Agricultural Productivity and Profitability in an Irrigated Mediterranean Catchment

Climate change is likely to have a profound effect on many agricultural variables, although the extent of its influence will vary over the course of the annual farm management cycle. Consequently, the effect of different and interconnected physical, technical and economic factors must be modeled in order to estimate the effects of climate change on agricultural productivity. Such modeling commonly makes use of indicators that summarize the among environmental factors that are considered when farmers plan their activities. This study uses net evapotranspiration (ET_N), estimated using EPIC, as a proxy index for the physical factors considered by farmers when managing irrigation. Recent trends suggest that the probability distribution function of ET_N may continue to change in the near future due to changes in the irrigation needs of crops. Also, water availability may continue to vary due to changes in the rainfall regime. The impacts of the uncertainties related to these changes on costs are evaluated using a Discrete Stochastic Programming model representing an irrigable Mediterranean area where limited water is supplied from a reservoir. In this context, adaptation to climate change can be best supported by improvements to the collective irrigation systems, rather than by measures aimed at individual farms such as those contained within the rural development policy.     

Analysis of Flow Behavior as Influenced by Reservoir with Flow Regularization

Understanding the behavior of reservoirs with flow regularization formed by hydroelectric power plants is essential for assessing water availability. The operationalization of reservoirs can be influenced both by climatic characteristics and by the consequences resulting from human actions in the basin. The objective of this study was to evaluate the existing relationships between the inflows and outflows of a reservoir, as well as with the conventional streamflow gauge stations downstream of the dam. Also evaluated were trends in the behavior of minimum, average and maximum flows, in the post-operation period, considering the characteristics of rainfall and irrigation in the region. The results indicated that reservoir operationalization is strongly related to the behavior of inflows. Moreover, a reduction was also verified in all the variables analyzed related to inflows and outflows, as well as in the stations downstream of the dam, except for the maximum flow in the station farthest from the reservoir, which showed a stationary behavior. The reductions in the flows may be related to the almost three-fold increase in the area irrigated by the center pivot in the basin; however, the same cannot be said in relation to the annual rainfall regime of the region, since it showed a stationary behavior for most of the stations evaluated. The work demonstrates the importance of trend analysis of flows over the years in order to identify possible factors responsible for their variability and assist in decision making regarding measures for the recovery and preservation of water resources.

     

基于SWAT模型的东江流域蓝水、绿水时空分布特征研究

基于SWAT(soil and water assessment tool)模型,对东江流域天然状态下的降雨径流过程进行模拟,进而评估流域蓝水、绿水的时空分布特征。结果表明:东江流域蓝水、绿水资源量都非常丰富,多年平均蓝水资源量274.67×108m3,绿水资源量178.72×108m3(主要以绿水流为主),蓝水资源是绿水资源的1.54倍。东江流域以蓝水为主的水资源构成体系主要是由流域湿热多雨的气候条件决定的。从时间变化来看,近年来东江流域蓝水资源、绿水资源、绿水流、绿水储皆无显著增加或降低趋势。从空间分布上来看,蓝水资源格局主要受降雨格局控制,而绿水资源不但受气候条件影响,还受流域下垫面的自然属性以及人类活动干扰,如土地利用方式、土壤类型等,分布格局较为复杂。     

New Insights Into The Natural Variability of Water Resources in The Lower Jordan River Basin

Water availability is naturally low in the Lower Jordan River Basin (LJRB) extending from Lake Tiberias to the Dead Sea, whereas water demand is high. Still, no basin-wide overview of naturally available surface water resources exists up to now. The aim of this study is to estimate these water resources through application of the TRAIN-ZIN model. This hydrological model combines physically-based and conceptual approaches to incorporate dominant processes of (semi-)arid areas in adequate temporal and spatial scale. An adequate space-time resolution is achieved by using rainfall radar data as model input. Three rainfall seasons are simulated: a drought, an average season and a wet extreme. Simulation results emphasize the non-linear behaviour of (semi-)arid systems and resulting impacts on the spatial and temporal variability of water resources. Basin averages of seasonal water balance components ranged between 65 and 489 mm (rainfall), 53 and 270 mm (evapotranspiration), 7 and 87 mm (overland flow), 4 and 129 mm (percolation). However, all values comprise enormous spatial variability. It is concluded that space-time variability must be considered for water resources assessment in the LJRB in order to make accurate predictions of future water availability.