Water Management Units Research Articles

Evaluation of uncertainty in capturing the spatial variability and magnitudes of extreme hydrological events for the uMngeni catchment, South Africa

Downscaled General Circulation Models (GCMs) output are used to forecast climate change and provide information used as input for hydrological modelling. Given that our understanding of climate change points towards an increasing frequency, timing and intensity of extreme hydrological events, there is therefore the need to assess the ability of downscaled GCMs to capture these extreme hydrological events. Extreme hydrological events play a significant role in regulating the structure and function of rivers and associated ecosystems. In this study, the Indicators of Hydrologic Alteration (IHA) method was adapted to assess the ability of simulated streamflow (using downscaled GCMs (dGCMs)) in capturing extreme river dynamics (high and low flows), as compared to streamflow simulated using historical climate data from 1960 to 2000. The ACRU hydrological model was used for simulating streamflow for the 13 water management units of the uMngeni Catchment, South Africa. Statistically downscaled climate models obtained from the Climate System Analysis Group at the University of Cape Town were used as input for the ACRU Model. Results indicated that, high flows and extreme high flows (one in ten year high flows/large flood events) were poorly represented both in terms of timing, frequency and magnitude. Simulated streamflow using dGCMs data also captures more low flows and extreme low flows (one in ten year lowest flows) than that captured in streamflow simulated using historical climate data. The overall conclusion was that although dGCMs output can reasonably be used to simulate overall streamflow, it performs poorly when simulating extreme high and low flows. Streamflow simulation from dGCMs must thus be used with caution in hydrological applications, particularly for design hydrology, as extreme high and low flows are still poorly represented. This, arguably calls for the further improvement of downscaling techniques in order to generate climate data more relevant and useful for hydrological applications such as in design hydrology. Nevertheless, the availability of downscaled climatic output provide the potential of exploring climate model uncertainties in different hydro climatic regions at local scales where forcing data is often less accessible but more accurate at finer spatial scales and with adequate spatial detail.

River basin management in Central Asia: evidence from Isfara Basin, Fergana Valley

Around the world, state water management organizations are the agents delegated to implement basin-level integrated water resources management strategies. In Central Asia, the hydrographic water management—deeming a river basin or a catchment area a proper water management unit—is a widely accepted concept. Yet, state water bureaucracies are incapable and/or reluctant to interact on water management with the “outsiders”, both domestically and internationally. To overcome this shortcoming, basin councils are promoted as formalized platforms to facilitate inter-sectoral dialogue, and likewise, to support local participatory processes within river basin planning and management. The approach offers a framework of integrating water sector planning and management with environmental, social and economic agendas of a given basin. State water management organizations are designated the role of technical secretariats of such basin councils which should be facilitating and helping to improve other stakeholders’ behavioral response in watersheds. The paper provides a comprehensive analysis of the process of implementation of the river basin model through the theory of change based on issues, challenges and recommendations identified in the transboundary Central Asian Isfara River Basin shared by Kyrgyzstan and Tajikistan.

Pollution of Wells’ Water with Some Elements, Fe, Mn, Zn, Cu, Co, Pb, Cd, and Nickel in Al-Jadriah District, Baghdad Government

Ninety six water samples were collected from eight wells in Al-jadriah district—Baghdad, from June 2010 to May 2011, and analyzed for presence of Fe, Mn, Zn, Cu, Co, Pb, Cd, and Nickel, using Atomic absorption method. Results revealed presence of only scanty amount of iron, Mn and Co, ranged from 0.09 - 0.29 ppm for iron and 0.016 - 0.339 ppm for Mn, and 0.01 - 0.732 ppm for Zn. Concentrations of other elements (Cu, Co, Pb, Cd, and Ni) were nil. All values were below the safe limit of water suitability for human uses, according to safe limits laid down by WHO (2011), Iraqi Measurement and Quality Control System and Iraqi Ministry of Environment. Wells’ water can be used under special management in Water management units.

Conceptual hydrogeological model and aquifer system classification of a small volcanic island (La Gomera; Canary Islands)

Conceptual groundwater models in volcanic island aquifers remain an issue in many regions of the world. This study takes advantage of the large number of outcrops exposing the inner structure of La Gomera (Canary Islands), due to its inactivity during the last 2.5Ma, to develop a conceptual groundwater model that helps improving groundwater resource management in the island and increasing knowledge in volcanic aquifers. Based on a volcanostratigraphic model, five hydrostratigraphic units have been defined that include two main aquifers and volcaniclastic deposits located between them that control the vertical movement of the groundwater. The island has been classified into four aquifer systems or water management units based on their hydrogeological features that permit a sustainable and independent management of the resources of one aquifer system in relationship with the other ones. The consideration of the complexity and heterogeneity of La Gomera geology has allowed to develop a conceptual groundwater flow model and to identify four general groundwater situations: 1) groundwater in the Upper aquifer discharging to the sea; 2) groundwater in the Upper aquifer springing out along the main ravines; 3) groundwater in the Basal aquifer impounded by dikes and; 4) groundwater in the Basal aquifer discharging to the sea.

Matching research and policy tools to scales of climate-change adaptation in the Murray-Darling, a large Australian river basin: a review

Climate change is likely to cause deleterious hydrological and ecological impacts in many of the world’s major river basins. Using the Murray-Darling Basin, Australia, as a case study, we present an adaptation framework which addresses the hydrological impacts of climate change at three spatial scales: the high-conservation value asset, the water management unit and the entire basin. At each scale, the appropriate scientific, policy and operational tools differ, though should be applied in concert. At the scale of the asset, hydrodynamic modelling has improved the capacity of site managers to anticipate the effects of management interventions. These models have also contributed to improve hydrological modelling of the water management unit. When combined with ecosystem response models, hydrological models can compare ecological outcomes over a range of timescales, leading to improvements in the representation of environmental requirements in water sharing plans. At the scale of the basin, the Australian government has used a legislative mechanism to set overarching ecological and diversion objectives. In addition, the purchase of water-use entitlements has created a flexible mechanism to use the water market as a climate-change adaptation mechanism, responding to the changing water availability and conservation priorities that emerge over the coming decades.

Effects of spatial scale on assessment of dissolved oxygen dynamics in the Atchafalaya River Basin, Louisiana

Low levels of dissolved oxygen (DO) are potential stressors of fishes and invertebrates in freshwater and marine systems. Because of the incredibly nutrient-rich and warm nature of the Atchafalaya River Basin (ARB), microbial decomposition in backwater areas with limited flow often results in potentially stressful, if not lethal, DO levels during and after the annual flood pulse. As water temperatures increase and flood levels fall, DO levels often stratify, restricting fish habitat. In order to better guide development of water management projects, we investigated the relationship between DO and DO stratification (DOD; surface DO − bottom DO) and a suite of environmental variables potentially linked to DO and DOD. Based on continuous monitoring data collected from 2000 to 2007, we used a variable selection procedure to construct statistical generalized linear models to describe the relationship between DO levels and DOD and several potentially important predictor variables at three spatial scales: the entire sampled area of the ARB; individual water management units (WMUs) or subunits (WMSs); and individual sampling sites. We conducted these analyses using models that assume the normal distribution and compared them to models that incorporate alternate error terms based on other error term distributions. Goodness of fit statistics suggested that our analyses best described the relationship between DO and structuring variables at the WMU/WMS scale. At this scale, water temperature, river stage height, current velocity, and to a lesser extent, water depth appeared to be the most important measured variables that influence DO levels. We suggest that management decisions at the WMU and WMS scales will offer the greatest potential benefits for improvement of DO conditions in the ARB.

Ontology-based simulation of water flow in organic soils applied to Florida sugarcane

An ontology-based simulation (OntoSim) is a unique data modeling environment where soil–plantnutrient processes are represented as database objects and the user-defined relationships among objects are used to generate computer code (Java) for running the simulation. The aim of this study was to model hydrologic processes of sugarcane-grown organic soils utilizing OntoSim in the Everglades Agricultural Area (EAA) of South Florida. This OntoSim-Sugarcane model describes the complex hydrology of subirrigation and open ditch drainage commonly used on Florida farms. Model calibration was conducted by (i) selecting rectangular farm water management units ( 0.65; coefficient of residual mass 0.55 and coefficient of residual mass <3%. It indicated that OntoSim-Sugarcane is able to simulate daily fluctuations of WT within the farm units and estimate lateral drainage/sub-irrigation and deep seepage that significantly contribute to the water balance at farms in the EAA. Thus, it can be a promising management tool to provide farmers with accurate assessment of water movement in this agricultural area.

Translating soil science into environmental policy: A case study on implementing the EU soil protection strategy in The Netherlands

The EU Commission has proposed a way forward towards a Thematic Strategy for Soil Protection based on the distinction of seven soil functions and eight threats. A Technical Working Group on Research defined some 200 general priority research areas in the context of the dynamic DPSIR approach considering drivers, pressures, states, impacts and responses. Though quite valuable as a source document, this may be too generic and academic to be a starting point for new, effective soil research in different regions of the EU. A six-step storyline procedure is therefore proposed aimed at deriving effective operational procedures for a water management unit in a given region, using available soil expertise and defining new research only where needed. The procedure, that was illustrated for a Dutch case study, consists of defining: (i) water management units (wmu's) in a landscape context; (ii) land-use, area hydrology and soil functions (iii) soil threats and relevant soil qualities; (iv) drivers of land-use change and their future impact; (v) improvement of relevant soil qualities; (vi) possibilities to institutionalize soil quality improvement as part of the EU soil protection strategy. A focus on regional wmu's is likely to result in a strong commitment of local stakeholders and governmental officials, allowing a more specific DPSIR approach. But this will only work if local officials also receive legal powers to develop and enforce codified ‘good practices’, to be developed in the context of communities of practice. Innovative research topics can be derived from a combined analysis of experiences within different communities of practice in different wmu's and should not be left to researchers to define.

Assessment of environmental flow requirements for river basin planning in Zimbabwe

There is a growing awareness and understanding of the need to allocate water along a river to maintain ecological processes that provide goods and services. Legislation in Zimbabwe requires water resources management plans to include the amount of water to be reserved for environmental purposes in each river basin. This paper aims to estimate the amount of water that should be reserved for environmental purposes in each of the 151 sub-basins or water management units of Zimbabwe. A desktop hydrological method is used to estimate the environmental flow requirement (EFR). The estimated EFRs decrease with increasing flow variability, and increase with the increasing contribution of base flows to total flows. The study has established that in order to maintain slightly modified to natural habitats along rivers, the EFR should be 30–60% of mean annual runoff (MAR) in regions with perennial rivers, while this is 20–30% in the dry parts of the country with rivers, which only flow during the wet season. The inclusion of EFRs in water resources management plans will not drastically change the proportion of the available water allocated to water permits, since the amount of water allocated to water permit holders is less than 50% of the MAR on 77% of the sub-basins in the country.