Defining a Topographic Index Threshold to Delineate Hydrologically Sensitive Areas for Water Resources Planning and Management

Hydrologically sensitive areas (HSAs) are runoff-generating areas often targeted for effective water resources planning and management actions. Commonly, HSAs can be mapped as areas in a landscape with a topographic index (TI) greater than a threshold level. This study explored the impact of a gradient of different TI threshold values for delineating HSAs using two popular TIs: a topographic wetness index (TWI) and a soil topographic index (STI). The resultant HSAs for each TI were compared to the Federal Emergency Management Agency (FEMA) 100-year floodplain map in New Jersey and its five water regions. Spatial comparison indicators were used to assess the spatial similarity between the HSAs delineated and the FEMA floodplain map. Such comparisons identified the threshold that delineated HSAs whose spatial distributions were most consistent with the FEMA floodplain at each spatial scale for each TI. For example, the identified threshold for using a TWI to delineate HSAs was 10.5 at the state level; however, this threshold varied by the water region. The HSAs delineated approximate the spatial extent of runoff-contributing areas to the 100-year flood relevant for water resources planning and management actions for flood hazard mitigation.

     

Romanian River Basins Lag Time Analysis. The SCS-CN Versus RNS Comparative Approach Developed for Small Watersheds

Romanian policy makers have to perceive that human intervention on river basins land cover is influencing rainfall-runoff relation and the used methodology cannot accurately estimate watershed surface flow transformations. Global water cycles and energy fluxes understanding is leading to better predictions of land atmosphere interaction and local hydro-climates evolution. The water transfer time determination from rainfall to runoff needs accurate measurements of river basins hydrological parameters. Here, we analyzed and compared the lag time value results of two different methodologies (curve number and rational methodology) used for 54 Romanian small catchment areas study. The focus of this paper is the lag time evaluation and interpretation for an effective implementation of the best methodology approach in the Romanian geographical space. Our research in small river basins was developed using remote sensing technology maps, GIS and environmental datasets in combination with field work on every drainage basin in order to assess the specific morphological features and validate the land cover typology. We found that Soil Conservation Service - Curve Number (SCS-CN) method is widely used according to USA landscape features classification, but not necessarily applicable to Romanian river basins characteristics. Our results show how the official Romanian rational methodology national standard (RNS) can be improved and the limits of SCS-CN method.

     

Flash flood early warning research in China

Abstract

Flash floods cause extensive loss of property and human life. Early warning systems present a more efficient approach to flood prevention and mitigation than engineering measures. This article reviews research on flash flood early warnings in China, including long-term prediction methods based on statistical regularity and flood mechanisms, and real-time warning indicators relying on multi-source data and automated systems. Current research shortcomings are discussed, and suggestions for future improvements are proposed. This research can provide public officials with knowledge of flash flood early warnings, influencing policy and protecting people from flash flood disasters.     

Changes in Irrigation Planning and Development Parameters Due to Climate Change

Considering changes in irrigation planning and development due to climate change is necessary to avoid system failure. This study demonstrated that changes in dependable flow and diversion water requirements in the future due to climate change will reduce potential irrigable areas. Climate change were based on the published projected climate in the study area. The dependable flow derived from successfully calibrated and validated Soil and Water Assessment Tool (SWAT) model streamflow simulations and the diversion water requirements based on the CROPWAT estimations of irrigation scheme were used to assess the potential irrigable areas. Substantial reductions in potential rice production areas (-4% to – 39%) were largely due to dwindled dependable flow (-1% to -25%) and an increase in diversion water requirement (+?7% to?+?26%). Reduction in potential irrigable area was projected during dry and normal years and may worsen towards the late twenty-first century under the worst-case climate scenario. Swelling of rivers during wet years will increase stream flows and potential irrigable areas but may also pose a danger of flooding. The development of water storage structures is necessary to reduce the adverse impacts of too much water during the wet years. Crop calendars should also be retrofitted to optimize the use of available rainfall during dry and normal years and climate-proof future irrigation systems. The results showed that it is necessary to incorporate climate change in irrigation planning and development. The methodologies described here could be used to climate-proof future irrigation systems in other areas in the Philippines and other countries.

     

Reassessing the Draft Articles on the Law of Transboundary Aquifers through the lens of reciprocity

ABSTRACT

In spite of groundwater’s growing importance, the 2008 Draft Articles on the Law of Transboundary Aquifers have yet to be fully adopted by the international community. As states contemplate the future of the draft articles, this article aims to reassess them through the lens of the legal principle of reciprocity. To do so, this article provides a framework for the analysis of law via reciprocity, followed by its application to the draft articles. Although this article primarily finds that they follow a reciprocal structure, it also identifies areas to be revisited, including sovereignty and recharge zone states.     

Planning Landscape with Water Infiltration. Empirical Model to Assess Maximum Infiltration Areas in Mediterranean Landscapes

Water infiltration is a natural process of landscape. The areas with high capacity to infiltrate are especially important in landscape planning, whose protection is crucial for the continuity of water flow, maximizing the recharge of aquifers, minimizing flooding risks and reduce soil erosion. The different interpretations of the criteria for the delimitation water infiltration areas, its imprecise legal nature and the progressive incentive for sustainable water and management policies, have created the need for an integrative and ecological based methodology that suppresses this gap at the landscape planning level. The aim of this research was to create a GIS model, based on ecological principles, that contributes to the delimitation of the maximum infiltration areas. The mapping of water-related systems guarantees the inclusion and protection of the hydrological cycle in the landscape planning. The application of the model in Almada Municipality, from Lisbon Metropolitan Area, allows the integration of the maximum infiltration areas in planning, municipal management and urban design. Almada is part of the recharge area of Tagus River aquifer. With the application of the proposed model, we concluded that 54 % of the municipality has maximum infiltration areas and 38 % of those are already impervious due to construction works. Finally, we concluded that this method should be applied in an early stage of planning, at several scales, leading to the definition of potential soil uses and priority intervention measures according with its ecological suitability.     

Groundwater Level Forecast Via a Discrete Space-State Modelling Approach as a Surrogate to Complex Groundwater Simulation Modelling

Reliable and precise forecasts of future groundwater level fluctuations are crucial constituents of sustainable management of scarce water resources and design of remediation plans. Groundwater simulations and predictions are often performed by employing physically based models, which are not applicable in a majority of water scarce areas around the globe, particularly in the developing countries like Bangladesh due to data limitations. On the other hand, data-driven statistical forecast models have demonstrated their suitability to model nonlinear and complex hydrogeological processes to forecast short- and long-term groundwater level fluctuations. The purpose of this effort is to propose a non-physical based approach by utilizing a discrete Space-State model as a prediction tool to forecast future scenarios of groundwater level fluctuations. The present study utilizes the prediction focused approach of the system identification process in which the overall objective is to develop a pragmatic dynamic system model. The performance of the proposed approach is evaluated for groundwater level data at three observation wells of Tanore upazilla in Rajshahi district, Bangladesh. Historical weekly time series data of groundwater level fluctuations from the three observation wells for 39 (1980–2018) years is used to develop the time series model, which is used for future groundwater level predictions for a period of next 22 years (up to 2040). The findings demonstrate the conceivable applicability of the proposed discrete Space-State modelling approach in forecasting future scenarios of groundwater level fluctuations in the selected observation wells.

     

Transposing of Water Policies from Developed to Developing Countries

Abstract

This paper examines the potential issues faced by developing country water authorities when subjected to the transposition of developed country water reform policies such as user pays. A case study approach employing two mutually compatible frameworks was adopted in examining these issues. The two frameworks used were a policy transposition comparative framework and an organisationally integrated planning and revenue modelling framework. The combined comparative and modelling approach provides a form of triangulation that, it is argued, strengthens support for the conclusion arrived at as a result of this study. The study found that, in terms of the case organisation, direct transposition of user pays policy was not sustainably viable. Areas for future research are identified, including improved policy review and adaptation mechanisms in facilitating bi-directional developed/developing country policy transposition.     

The Impact of Climate Change on Hydro-Meteorological Droughts Using Copula Functions

Climate change has made many alterations to the climate of earth, including hydro-climatic extreme events. To investigate the impact of climate change on hydro-meteorological droughts in the Kamal-Saleh dam basin in Markazi province, Iran, proportional to future climate conditions, a new and comprehensive index was developed with the aim of accurately estimating drought in a more realistic condition. This aggregate drought index (ADI) represented the main meteorological and hydrological characteristics of drought. Temperature and precipitation projections for future climates were simulated by five CMIP5 models and downscaled over the study area during 2050s (2040–2069) and 2080s (2070–2099) relative to the baseline period (1976–2005). By fitting five univariate distribution functions on drought severity and duration, proper marginal distributions were selected. The joint distribution of drought severity and duration was chosen from five types of copula functions. The results revealed that in future, severe droughts are expected to frequently occur in a shorter period.

     

Scientific and Engineering Issues in Design and Forecasting for Floods

ABSTRACT

The article assesses problem areas identified in publications dealing with the 1993 flood on the Mississippi and Missouri river basins. This event, because of its long duration, gave federal and state agencies an unequaled opportunity to marshal1 data-gathering teams who collected data as the event progressed. Recent development of new instruments and strategies for measuring streamflows and bathymetry quickly and accurately enhanced this opportunity Major areas deserving future emphasis are identified as development of highly trained teams for gathering, transmitting, and assembling field data during large flood events, and refinement of methods of real-time forecasting.     

Impact of Climate Change on Future Flood Susceptibility: an Evaluation Based on Deep Learning Algorithms and GCM Model

Floods are common and recurring natural hazards which damages is the destruction for society. Several regions of the world with different climatic conditions face the challenge of floods in different magnitudes. Here we estimate flood susceptibility based on Analytical neural network (ANN), Deep learning neural network (DLNN) and Deep boost (DB) algorithm approach. We also attempt to estimate the future rainfall scenario, using the General circulation model (GCM) with its ensemble. The Representative concentration pathway (RCP) scenario is employed for estimating the future rainfall in more an authentic way. The validation of all models was done with considering different indices and the results show that the DB model is most optimal as compared to the other models. According to the DB model, the spatial coverage of very low, low, moderate, high and very high flood prone region is 68.20%, 9.48%, 5.64%, 7.34% and 9.33% respectively. The approach and results in this research would be beneficial to take the decision in managing this natural hazard in a more efficient way.

     

大兴机场海绵设施雨洪控制效果模拟

以大兴机场海绵系统为例,根据降雨径流资料,建立暴雨雨水管理模型(storm water management model,SWMM),模拟不同海绵设施组合情景下的水文过程。结果表明:在不同设计暴雨条件下,绿色基础设施、景观湖以及组合方案均能削减洪峰流量、延迟洪峰时刻;组合方案的雨水控制效果最为显著,5 a重现期下,出口处洪峰流量削减率和雨水总量控制率分别达41.5%和79.9%;景观湖的蓄滞作用在不同的重现期下对出口流量的影响时段不同,景观湖在低重现期下蓄积降雨过程中的雨水,削减降雨初期外排出口的流量,而在高重现期下蓄积空间主要用于降雨后期的雨水汇流的收集,在出口段明渠退水过程中减少外排雨水;绿色基础设施在上游区域的溢流量削减率达到10.6%,在洪峰削减、延迟峰值时刻上表现明显;上游连接景观湖后造成的回流会导致退水时长增加,在高重现期下回流雨水占用明渠蓄水空间,可能增加上游管网的溢流风险。     

Flood Vulnerability Analysis by Fuzzy Spatial Multi Criteria Decision Making

Prioritization the sub-basins available in a basin to flood vulnerability analysis can be discussed in the form of a spatial multi criteria decision making (SMCDM) problem. In this research a fuzzy planning support system based on the spatial analysis using tow multi criteria decision making methods, Analytic Hierarchy Process (AHP) and TOPSIS (Technique for order-preference by similarity to ideal solution) is used. AHP method is used to determine the structure of decision making process and to estimate criteria weights and TOPSIS model is used to rank the sub-basins of Tehran urban basin as a study area regarding the flood vulnerable areas. Also in order to perform spatial analysis for decision-making process, a developed toolbox is used within the Geographic Information System (GIS). In this research a model is presented in which some vague concepts such as weight of decision making criteria are expressed in the form of linguistic variables to be converted to triangular fuzzy numbers. Finally, the sensitivity of model was analyzed by changing the weights of decision making criteria and providing of ranking scenarios. The results show the optimum alternatives for mitigation flood vulnerability in the study area.

     

Multicriteria Analysis for the Assessment of Flow Release Scenarios from a Hydropower Plant in the Alpine Region

The Alpine region is an area of conflict between the significant demand for hydropower (HP) generation and the protection of landscape and aquatic ecosystems. Decision Support Systems, like multicriteria analysis (MCA), represent suitable tools to support decision-makers and stakeholders in managing the use of water resources in a more sustainable way. Based on a set of “quality indexes” identified in a previous study, the present paper analyzes the use of MCA in a real case study of HP sustainable management in Aosta Valley, one of the most important Italian regions for HP production. The Simple Additive Weighting (SAW) methodology was applied to quantify the flow to be released by an existing HP plant, in order to balance production needs and watercourse environmental conditions protection considering four criteria (Energy, Environment & Fishing, Landscape, and Economy). The decisional process was developed within a collaborative and participatory framework, involving key stakeholders in every decision-making step, and the obtained results were officially adopted by the Regional Government. In the paper, some innovative aspects of the case study are presented and discussed, like the elaboration of reactive indicators related to the watercourse discharge, progressively updated with the stakeholders along the process, and the definition of “real-time” alternatives, relating the flow releases to the natural discharges in the watercourse. Finally, some weaknesses of this MCA approach are identified and suggestions for improvements in future experimentations are proposed.

     

An Assessment of Climate Change,Water Resources,and Policy Research

ABSTRACT

A significant climate change can affect water resources and result in social and/or environmental impacts that can become policy issues. Review of the research in this emerging field of climate, water and policy reveals certain key issues that affect the transfer of information to policymakers. It also reveals the necessity for interdisciplinary analyses, a lack of information about parts of the hydrologic cycle, and the limited views many hydrologists have about climate changes and how to deal with them. The emphasis of recent research has been on effects on precipitation of CO, induced global warming on how climate changes might alter extreme events (droughts and floods), the relationship of climate alterations and water quality, and development of methods to better ascertain linkages of climate, water, and society. Policymakers attempting to address the effects of climate change on water resources generally ask six questions including: (1) the type of climate change apt to occur; 2) the changes beyond our recent (100-year) experience; 3) whether the changes can be predicted; 4) the certainty of change/s predicted; 5) the effects (social and environmental) that will occur; and (6) the potential adjustments needed.

Efforts to address adequately these questions are often hindered by four problem areas that need attention. First, climate impacts research is still in the developmental stage. Second, knowledge about certain hydrologic cycle variables is lacking and in particular, the interactions between climate and water quality. Third, many hydrologists assume stationarity in climate and find it difficult to accept and utilize climate change concepts. Finally, the impact of information on climate-water issues on the policy process is less than adequate often because scientists poorly understand the policy process.     

Factors Influencing Per Capita Water Consumption In Urban Areas Of Developing Countries And Their Implications For Management,With Special Reference To The Khartoum Metropolitan Area

ABSRTACT

The fast growing population in Third World countries and the limited physical resources in rural areas have led to the dramatic expansion of the urban areas of these countries. It is now recognized that when planning for the development of these areas, early consideration must be given to the difficulties and cost of providing potable water equitably to all users. Detailed studies are necessary for particular situations so as to provide a basis for better management practices.

Khartoum, a growing urban area in Sudan, has been chosen as a case study. A proposed framework and technique of analysis is shown. Factors influencingper capita consumption are correlated and mathematical models have been generated for the two distinct classifictions of consumers: (1) consumers with piped supply and (2) consumers obtaining water from water vendors or from standpipes (squatter settlements).

The most significant factors affecting the consumption appear in the fitted equations. Of these factors, the number of occupants in the household influences the per capita consumption but at a decreasing rate. Price has a significant impact on demand: price elasticities of about -0.60 and -0.78 are obtained for households with piped connections and squatter areas respectively. Water utility authorities can use price as a tool to ration or discourage water consumption in the piped connection households and to increase the rate of consumption in the squatter areas.     

LiDAR based hydro-conditioned hydrological modeling for enhancing precise conservation practice placement in agricultural watersheds

High resolution Light Detection and Ranging (LiDAR)-derived Digital Elevation Models (DEMs) improve hydrologic modeling and aid in identifying the targeted locations of best conservation practices (CPs) in agricultural watersheds. However, the inability of LiDAR data to represent the conveyance of water under or through the surfaces (i.e., bridges or culverts) impedes the simulated flow, resulting in false upstream pooling. Improper flow simulation affects the accuracy of pollutant load estimations and targeted locations delineated by watershed models or models built upon hydro-conditioned DEMs (hDEM). We propose a novel approach of Hydro-conditioning to modify LiDAR imagery through breach lines, which is essential to accurately replicate the landscape hydrologic connectivity. We compared variations in outcomes of Agricultural Conservation Planning Framework (ACPF), based on manual and automated hDEMs for Plum Creek watershed, Minnesota. The derived flow network, catchment boundaries, drainage areas, locations/number of practices depend on the chosen hDEM. Locations, size and shape of bioreactors, drainage management, farm ponds, nutrient removal wetlands, riparian buffers are severely affected by hydro-conditioning. Shuttle Radar Topography Mission (SRTM) validation of hDEMs showed that Mean Average Percentage Deviation (MAPE) for automated and manual hDEMs is 1.34 and 0.998 respectively. Also, proximity analysis with a buffer of 200 m showed that CPs’ locations delineated by manual hDEM match better with the existing ones as compared to automated hDEM. Results indicate that coupled approach of using automated and manual ‘hDEM’ is best suited for guiding stakeholders towards the field-scale planning in a cost-saving manner.

     

Using Similarity Analyses to Scale Out Research Findings Across Andean Watershed Basins

Abstract

Strategic research in agriculture and natural resources carried out by international research centers is deemed a public good and should, sooner or later, be put into the hands of development, governmental and non-governmental organizations. However, this research is usually done at specific pilot sites; there is a greater need to know how representative those sites are in relation to the diversity of contexts in other locations. Such is the case with the Challenge Program on Water and Food (CPWF), a global initiative in water research promoted by the Consultative Group on International Agricultural Research (CGIAR), which is developing and implementing strategic research in nine basins located in the tropics of Africa, Asia and South America. Given that resources are not available to collect data from the whole of the region, pilot sites are needed. It is hoped that research outputs obtained in the selected pilot sites can be the basis for scaling out solutions to similar situations in neighbouring or adjacent areas in same or different basins.

In order to contribute to the scaling-out process, different classification methodologies were applied to determine how specific watershed basins are representative of larger areas. The Andean eco-region served as a case study but the methods can easily be applied in other regions. The spatial diversity of biophysical and social conditions across the Andes requires careful site selection. Two methods, a combination of Weight of Evidence (WofE) and Logistic Regression (LR) methods and Fast Cluster analysis, were used to determine the similarity of selected sites with those excluded. A 1-km study resolution covering most of the Andes eco-region included annual rainfall, elevation, length of growing period, land cover, roads and population density as the key variables. Results showed complementarities between the two methods in presenting a probability surface of similarity across the Andes and a clustering of similar sites inside and outside the pilot basins. The output information forms a strong basis for devising plans to scale out research findings from the pilot basins to the whole region.     

Progress in ecological and environmental water requirements research and applications in China

Abstract:

With economic development, as well as population growth, the conflict between water supply and demand has become more and more acute in China, and it has been aggravated further by the irrational utilization of water resources. As a result, the deterioration and destruction of the eco‐environment have become increasingly serious. In order to effectively protect ecosystems and improve their ecological conditions, many studies on ecological and environmental water requirements (EEWR) have been carried out in China. In this paper, the concept and characteristics of EEWR are addressed, and the main advances of EEWR research and applications in China are summarized in four types of systems including studies on rivers, vegetation, lakes and wetlands, and groundwater. In conclusion, issues necessary to be studied further in the future are put forward.     

Water Demand Theory and Projections in South Africa

Abstract

This study estimates Rand Water's water demand in South Africa for 2000 to 2020. It indicates lower growth in water consumption in the foreseeable future than in the past century. The reduced growth is due to: Economic slowdown (international and South African); Lower standard of living/residences for the “white” population; Corresponding decrease in formal business growth; Limitations of services in built up areas; Increased water costs; Improved loss control; HIV/Aids; Unwillingness of informal residents to contribute for services. This is offset by: Migration of poor to cities and creation of peri-urban growth; Increased standards for previously disadvantaged people; Improved health facilities; Growth in informal economy; New political freedom. A net growth of 2 percent annually is forecast. A statistical approach is adopted to obtain confidence limits for individual sectors. A decomposed demographic model is developed and used to predict water demand until 2020. A wider uncertainty in future consumption is foreseen. Conservative planning is recommended for future water resource projects, e.g. low capital, and operating intensive schemes are preferable. A methodology for planning in the face of uncertainty and low growth is developed.