University of Twente Student Theses

Spatial dynamics in allocation of scarce water : a study about inter-annual and spatial dynamics in agricultural land use and irrigation water use under changing water availabilities around the Orós eservoir in the Northeast of Brazil

Leskens, J.G. (2006) Spatial dynamics in allocation of scarce water : a study about inter-annual and spatial dynamics in agricultural land use and irrigation water use under changing water availabilities around the Orós eservoir in the Northeast of Brazil.

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Abstract:	Conflicts in distribution of available water resources are common in the semi-arid Northeast of Brazil, mostly because of the scarcity of availability of water resulting from climatic conditions. Lacking knowledge about spatial dynamics of land use and its irrigation water use under changing water availabilities limits the determination of suitable solutions in finding the best way to allocate the scarce and strongly varying amount of available water. The goal of study is to get more knowledge about the spatial dynamics of agricultural land use and irrigation water use under different situations of water availability around strategic water reservoirs in the semi-arid northeast region of Brazil. This is done by analyzing these aspects a spatial way, using GIS and Remote Sensing-techniques, for a research area around the Orós reservoir located in the Northeast of Brazil, during the dry seasons in 2000 to 2005. Firstly a downscaling is carried out to 6 ‘areas of interest’, each mainly supplied by one source of water availability. Four aspects of water availability could be distinguished in the research area: rainfall, river discharges/reservoir releases, reservoir volumes and locally stored runoff. Each type of water availability is quantified for each area of interest. Secondly the agricultural land use, as largest water user, is determined by applying a land cover classification to satellite images of each year. Thirdly the irrigation water use of each area of interest in each dry season within the research period is estimated by using the Cropwat model, a model able to calculate crop irrigation requirements. The results of these three components are analyzed in a inter-annual way (how are the components evolving during the research period in a particular area of interest) and in a spatial way (how do the components of different areas of interest influence each other during the research period. The analysis showed that the different types of water sources have different spatial and temporal ranges and different water availabilities. This determines the way in which agricultural water users, dependent on a certain water source, effect the water availability of other agricultural water users. Rainfall and river discharge in the dry season are far too low to fulfill the irrigation water requirement of the areas that are connected to these water sources. Locally stored water is only local available; irrigation water use of this source does not noticeable effect downstream water availabilities. Water users around the reservoirs (upstream, edge, downstream) in the area influence each others water availability on different time scales: The relevant time scale around small reservoirs are estimated on 1-3 years and > 10 year around the largest reservoir. It is recommended to take these different time scales into account by defining water management actions. The type of crops grown effects the course of the irrigation water use: paddy and beans require a shorter but a somewhat more intense water supply than banana. The reservoir edge is therefore suitable for temporal crops requiring intense water supplies. Areas downstream of reservoirs are more suitable for banana in case the intense water requirements of paddy and beans cannot be fulfilled. Banana is infeasible in areas where land availability can be temporally limited by overflow.
Item Type:	Essay (Master)
Clients:	ITC
Faculty:	ET: Engineering Technology
Subject:	56 civil engineering
Programme:	Civil Engineering and Management MSc (60026)
Link to this item:	https://purl.utwente.nl/essays/57283
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