Mukand S. Babel

Non-deposition design criteria for sewers with part-full flow

In this study, the existing self-cleansing design criteria for sewers based on minimum velocity and minimum bed shear stress have been reviewed. Based on several laboratory experiments, the study then develops non-deposition criteria for non-cohesive sediment in uniform flow. The developed criteria take into account geometry of flow sections, hydraulic and sediment properties based upon three dimensionless parameters, namely, the densimetric Froude number, the volumetric sediment concentration and the relative grain size. The proposed criteria provide improved estimates of self-cleansing minimum velocities compared to the traditional one-parameter design criteria and agree well with the well-known existing design criteria, namely, Mackes formula for suspended load and Mays formula for bed load. The present study therefore contributes new non-deposition design criteria for sewers with part-full flow in the range of the experiment conducted and yet which are simple for practical applications. Further research work is required to substantiate the preliminary character of the results presented for wider application of the proposed self-cleansing design criteria.

Indigenous systems of conflict resolution in Oromia, Ethiopia

This paper describes the role of the Gadaa system, a uniquely democratic political and social institution of the Oromo people in Ethiopia, in the utilization of important resources such as water, as well as its contribution in conflict resolution among individuals and communities. It discusses ways to overcome the difference between customary and statutory approaches in conflict resolution. A synthesis of customary and statutory system of conflict resolution may facilitate a better understanding that will lead to improved management of resources, which are predominant variables for the socio-economic development of the country. It suggests that top-down imposition and enforcement of statutory laws that replace customary laws should be avoided. Instead, mechanisms should be sought to learn from the Lubas, elders who are knowledgeable in the Gadaa system, about the customary mechanisms of conflict resolution so as to integrate them in enacting or implementing statutory laws.

Vulnerability of freshwater resources in large and medium Nepalese river basins to environmental change.

This paper discusses vulnerability of freshwater resources in large and medium Nepalese river basins to environmental change based on evaluation of water resource availability and variation, resource development and use, ecological health and management capacity; and compares the situation with selected sub-basins of the Ganges and the Mekong basins in Asia. Results suggest that water resources in the medium river basins are more vulnerable than in the large basins; and Nepalese basins, in general, are more vulnerable than other selected basins in the Asian region. The vulnerability in the Nepalese basins is more related to poor management capacity followed by resources variation and the least to development pressure. The poor management capacity is mainly related to low productivity of water use and the resources stress is related mainly to variation of the resource.

Climate change and water resources in the Bagmati River Basin, Nepal

This paper characterizes potential hydrological impact of future climate in the Bagmati River Basin, Nepal. For this research, basinwide future hydrology is simulated by using downscaled temperature and precipitation outputs from the Hadley Centre Coupled Model, version 3 (HadCM3), and the Hydrologic Engineering Centers Hydrologic Modeling System (HEC-HMS). It is predicted that temperature may rise maximally during the summer rather than winter for both A2 and B2 Special Report on Emissions Scenarios (SRES) scenarios. Precipitation may increase during the wet season, but it may decrease during other seasons for A2 scenario. For B2 scenario, precipitation may increase during all the seasons. Under the A2 scenario, premonsoon water availability may decrease more in the upper than the middle basin. During monsoons, both upper and middle basins show increased water availability. During the postmonsoon season, water availability may decrease in the upper part, while the middle part shows a mixed trend. Under the B2 scenario, water availability is expected to increase in the entire basin. The analysis of the projected hydrologic impact of climate change is expected to support informed decision-making for sustainable water management.

Indicator-Based Approach for Assessing the Vulnerability of Freshwater Resources in the Bagmati River Basin, Nepal

To assess the vulnerability of water resources in the Bagmati River Basin in Nepal, this paper adopts an indicator-based approach wherein vulnerability is expressed as a function of water stress and adaptive capacity. Water stress encompasses indicators of water resources variation, scarcity, and exploitation and water pollution, whereas adaptive capacity covers indicators of natural, physical, human resource, and economic capacities. Based on the evaluation of eleven indicators, which were aggregated into eight vulnerability parameters, an increasingly stressful situation and lack of adaptive capacity became evident. Considerable spatial variation in indicator values suggests differential policy options. While the northern parts need attention to reduce pollution loading and conserve vegetation cover, the southern parts need improvements in physical capacity, i.e. water infrastructures. The comprehensive and easily interpretable findings of the study are expected to help decision makers reach sound solutions to reduce freshwater resources vulnerability in the Bagmati River Basin, Nepal. With its inherent flexibility, the approach has demonstrated its potential for application in different times and areas for monitoring and comparison purposes.

Challenges for Sustainable Management of Groundwater Use in Bangkok, Thailand

An overview of groundwater development in Bangkok, Thailand, is provided and the paper highlights the environmental consequences of unplanned large-scale groundwater utilization. The effectiveness of the control measures adopted so far to address the issue of land subsidence is discussed. Recent initiatives and studies are analysed and the impediments to effective implementation of control measures are identified. Challenges faced by the Department of Groundwater Resources, which is responsible for groundwater development and management, are indicated. Recommendations are then put forward for improvement of the groundwater management system.

Simulation of infiltration from porous clay pipe in subsurface irrigation

Abstract Advances in the traditional method of subsurface porous clay pipe irrigation rely on knowledge of the distribution of water in the soil. Knowing the relationships among the hydraulic and physical parameters in the system is important for both the design and management of the system. To simulate the infiltration from the porous clay pipe and predict the wetted zone geometry in the soil, a computer model is developed herein. Laboratory experiments were conducted on soil samples representing two different soil textures in a specially designed bin to understand the flow phenomenon and to validate the developed model. In a given soil texture, the installation depth of the pipe and the volume of water applied in the soil are the major factors affecting the wetted zone. The relationships among various parameters, namely lateral spacing, installation depth, irrigation run time, hydraulic conductivity of the body of the pipe, and hydraulic head in the system, were established using the developed model.

Fingered preferential flow in unsaturated homogeneous coarse sands

The occurrence of fingered preferential flow depends on both flow and porous media characteristics. The boundary condition of unsaturated infiltration has been investigated to assess whether it produces unstable wetting in homogeneous coarse sands. Laboratory tracer experiments were conducted in two coarse sand materials; for each sand material two initial conditions of air dry and field capacity were considered. Results indicate that the commonly occurring process of nonponding rainfall can provoke fingered preferential flow in homogeneous sandy soils. This phenomenon is very predominant in dry as compared to wet initial conditions. Models of water flow and solute transport in uniform coarse soils should incorporate the effects of such fingered flow phenomenon.

Hydrology, management and rising water vulnerability in the Ganges–Brahmaputra–Meghna River basin

A water vulnerability analysis is made of how sensitivity characteristics of the Ganges–Brahmaputra–Meghna (GBM) River basin may affect adaptive capacity. A co-riparian ‘country perspective’ highlights the importance of local level management actions. Results reveal that vulnerabilities in India and Bangladesh stem from hydrological and ecological factors, but are more linked to poverty and underdevelopment in Nepal. Poor political governance and underinvestment in the water sector add to vulnerability in Bangladesh and Nepal. Overall, Bangladesh is the most sensitive country while Nepal has the least capacity to adapt.

Evaluation of the Effectiveness of Water Management Policies in Bangladesh

Water resources development and management policies initiatives in Bangladesh are primarily driven by the need for sufficient food grain production for the countrys teeming population and curtailing the perennial flooding problems. It is therefore necessary to investigate whether or not these objectives are being met. The aim of this study is to evaluate the impacts of past water resources development and management strategies on agriculture, food security, flood management and socio-economic development in Bangladesh. The research is based on the historical data of the relevant parameters of the water resources management over the period 1947–2005. The outcomes of the study demonstrate that past policies and strategies of water development have resulted in significant irrigation expansion, especially through intensified groundwater utilization, which has helped to achieve the countrys primary objective of self-sufficiency in food production. However, the provision of safe drinking water and sanitation facilities still remains a challenge in the country. Similarly, the impact of the flood control policies was diverse with success mostly apparent with regard to protection against modest events, while catastrophic, extreme events still effectively defying answer.