Ian K. Smout

Irrigation distribution networks' vulnerability to climate change

Climate change will lead to changed demands on existing irrigation systems. This paper presents a methodology for investigating the performance of irrigation networks under climate change, and applies this to an irrigation network in Cordoba, southern Spain. The methodology uses emission scenarios (A2 and B2) developed by the Intergovernmental Panel on Climate Change. A global climate model (HadCM3) is used with downscaling to predict climate variables for 2050 and 2080 under the emission scenarios. European agricultural policy scenarios are used to predict future cropping patterns. Irrigation water requirements are then estimated for various combinations of these climate and cropping pattern scenarios, and the performance of the irrigation network is evaluated in terms of the equity and adequacy of pressure at the outlets, using EPANET. The methodology was applied to the Fuente Palmera irrigation district, which supplies water on-demand for drip irrigation. The results show that climate change would have a major impact on network performance with the existing cropping pattern, but that expected changes in cropping pattern would reduce this impact.

Application of Watershed-Based Tank System Model for Rainwater Harvesting and Irrigation in India

The SOFTANK model optimally designs the watershed-based tank system by simulating field, tank, and groundwater balances. We applied this model to a small watershed consisting of six tanks (small reservoirs) in the semiarid region of India. We evaluated the existing tank system in this watershed and compared it to a one-tank system. Results showed that one tank at the outlet of the watershed would have been more beneficial [with benefit-cost (BC) ratio of 1.80] than the existing six-tank system (with BC ratio of 1.71). Finally, we performed the analysis for obtaining the optimal tank system for the watershed, and we found that the tanks for irrigation purposes are not economical for the small watershed. The groundwater source was enough for irrigation, so any additional investment in the tanks would be uneconomical. The results demonstrate the importance of the watershed-based tank system approach to design.

Optimum Design of a Watershed-Based Tank System for the Semiarid and Subhumid Tropics

Small reservoirs known as tanks are constructed in the watersheds of arid, semiarid, and subhumid regions of India to provide supplementary or protective irrigation to crops during dry spells of the monsoon season or full irrigation during the postmonsoon season. The stored water in tanks or recharged groundwater is used for this irrigation. Several models have previously been developed to design the capacity of individual tanks. However, for optimum utilization of water generated in a watershed to meet the demands for irrigation and for downstream release, it is necessary to design the tanks together in terms of their number, locations, and capacities. A comprehensive methodology for this is presented using stream points, i.e., possible tank locations on the main stream(s) in the watershed. Tank strategies (combinations of numbers of tanks, their locations at stream points, and tank types) are then generated for the identified stream points. Subsequently, fields in the watershed are assigned to the catchment and the command of different tanks of a specified tank strategy. Simulation of field, tank, and groundwater balance is then carried out on a daily basis, from which optimum tank dimensions are obtained for a specified tank strategy. The optimum tank strategy and corresponding optimum tank dimensions are obtained by investigating all the possible tank strategies.

Use of low-pressure pipe systems for greater efficiency

Abstract Low-pressure pipelines on surface irrigation distribution systems serve about 4.5% of the world irrigation area. The main benefits compared with open channels are reduced leakage rates and land-take requirements, and flexibility in irrigation timing which is important for diversified cropping systems. Fieldwork data on these are presented from Bangladesh.

The divergence between acceptability of municipal services and urbanization in developing countries: insights from Accra and Sekondi-Takoradi, Ghana

Abstract In most developing countries, the provision of municipal services and infrastructure invariably fails to match the pace and demands of urbanization. The outcome is often increased informality due to improper planning, official bureaucratic barriers and perhaps insufficient and shrinking public resources, which then makes leveraging private capital for public service provision imperative. Drawing on in-depth qualitative fieldwork in two Ghanaian cities, this paper aims to extend literature on the divergence between service provision and urbanization in developing countries. More specifically, it attempts to qualify recent macro-level data indicating that access to water, sanitation and electricity services in Accra and Sekondi-Takoradi is improving substantively. Contrary to dominant policy narratives circulating in Ghana, we illustrate how the acceptability of key municipal services within urban settings is often inadequate, and how acceptability is tied to spatial and temporal factors. We then identify and examine the reasons underpinning these variations. Through exploring residents’ perceptions of key services, and examining critically the possibility and feasibility of meeting urban service needs through leveraging private resources, this paper contributes to broader academic debates over urban service provision, while also feeding into contemporary policy discussions concerning how to achieve several of the Sustainable Development Goals by 2030.

Computer simulations in games for training in irrigation management

Since 1982, a number of training systems have been developed, based on simulation and gaming techniques. The main objective has been to familiarise and motivate managers and potential managers in the effective utilisation of water resources in general and in irrigation operation in particular. This paper describes the approach which has been followed for the development of games based on computer simulations, together with an outline of the computing techniques, and descriptions of the various games which have been developed.

Wastewater Treatment Capacity, Food Production and Health Risk in Peri-urban Areas: A Comparison of Three Cities

Growing cities and their demand for water challenges the management of water resources and provides opportunities for wastewater use in irrigated agriculture. In the cases studied, large volumes of fresh water are extracted from sources often located increasingly further away from the city, while investments in wastewater disposal often lag behind. The resulting environmental impact in peri-urban areas can have multiple consequences for public health, in particular through the use of untreated or poorly treated wastewater in irrigated agriculture. Despite significant efforts to increase wastewater treatment, substantial volumes of untreated wastewater are applied in irrigated agriculture in Addis Ababa (Ethiopia), Accra (Ghana) and Hyderabad (India). Additional options for safeguarding public health are required to allow the cities to maintain the benefits from already existing, but largely informal, wastewater reuse.

AWAM-A model for optimal land and water resources allocation

This is a conference paper. Further details of this conference can be found at: http://content.asce.org/conferences/thailand09/index.html

Development of an Object — Oriented Hydraulic Simulation Model for Canal Networks Using a Relational Database

Canal models can be used to understand the hydraulic behaviour of complex irrigation networks. Numerical methods such as the finite difference (FDM), finite element (FEM) and finite volume methods (FVM) have become well-established tools in water and hydraulic engineering. While finite difference schemes are widely used in hydraulic engineering, they are not suitable for certain types of problems, particularly flows which exhibit strong discontinuities. These limitations can be dealt with by introducing shock-capturing techniques. FVM with shock capturing schemes applied to the shallow water equations is thus suitable for modelling a variety of flows, particularly the propagation of shocks and water level disturbances throughout an irrigation network. This paper describes an object-oriented implementation of the finite-volume based numerical algorithm for the solution of the 1-D shallow water equations. The model solves the hydrostatic St. Venant equations using an explicit FVM with a Godunov-type high-resolution shock capturing technique. The Riemann problem for the 1-D shallow water equations is solved using an exact Riemann solver capable of handling dry bed conditions. The model is developed for irrigation canal networks with an object-oriented approach using Java and MySQL as a back-end for effective storage and retrieval of the data. The model has been tested for mass conservation and ramp discharge tests. Further development and testing are in progress.