Operational Remote Sensing for Sustainable Development

M. Molenaar, G.J.A. Nieuwenhuis, R.A. Vaughan

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781000150957
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

This text presents papers from the 18th EARSeL Symposium, held in Enschede, Netherlands. The papers are followed by application-oriented contributions on specific themes such as land use and nature management; water quality and pollution monitoring; and coastal zone management.

1 Remote sensing for sustainable development: State of the art

The use of remote sensing to improve irrigation water management in developing countries

W.G. M. Bastiaanssen

International Irrigation Management Institute (IIMI), Colombo, Sri Lanka & International Institute for Aerospace Survey and Earth Sciences (ITC), Department of Water Resources, Enschede, Netherlands

ABSTRACT: The pressure on water availability increases worldwide, and this is felt specially in the arid and semi-arid tracts. Several countries located in arid belts already use more surface and groundwater than is replenished naturally. Irrigated agriculture is a big water consumer and irrigation water needs to be utilized with greater concern. The Governments of developing countries are faced with a data crisis related to land and water management issues. Water balance determinations are compelled by their scale variations and cannot be straightforwardly interpreted from point observations. It is expected that remote sensing technologies can help understanding the rural environmental conditions (vegetation cover, leaf area index, land use, crop production, salinization) and the hydrological cycle when remotely sensed data is integrated with appropriate distributed hydrological models and GIS databases (rainfall, soil moisture, evapotranspiration, surface runoff, groundwater recharge). It is also expected that the productivity of water in river basins, water scarcity analysis and the sustainability of agro-ecosystems can be improved if large scale information systems based on emerging technologies will be made operational.

1 INTRODUCTION

In recent years, there has been an increasing awareness that water will be the critical natural resource issue within, and between, many countries in the next century (e.g. Serageldin, 1995; Biswas, 1995; Postel et al., 1996; Gleick, 1997). Frederickson (1996) mentions that a world population growth of 1 billion in the next decade and 2 billion in the next two decades is forecast and that this growth will place immense demands on the water resources of developing countries. By 2025, as many as fifty-two countries inhabited by some 3 billion people will be plagued by water stress or chronic water scarcity. World-wide, more water is diverted to and consumed by irrigated agriculture than any other economic sector. China, India, Pakistan, former USRR and US form 62 % of the total area irrigated in the world (Ghassemi et al., 1995). Agriculture accounts for some 63% of the world’s use of fresh water (about 70% to 90 % in the developing countries). Food projections for 2040 reveal a need for a two to three-fold increase in food productivity, as compared to 1990 (Penning de Vries et al., 1995). In many developing countries, the scarcity of water is becoming a significant constraint on food production, and a shortage in water and food may affect socio-economic stability.

One of the critical issues in land and water resources analysis is the availability and reliability of geographically distributed data. Irrigated river basins may comprise several natural environments and encompass different agro-ecosystems. A thorough hydrological understanding between and within agro-ecological zones is paramount to assess effective use of water available. The configuration of rainfall, snow melt, evapotranspiration, groundwater storage and runoff among others, is a valuable piece of information to understand whether water resources are sufficient and sustainable in the face of demands from different sectors. Our hydrological knowledge of river basins is, however, far from being sufficient and consistent to make a thorough analysis of water flow at larger scale feasible. For instance water use by evapotranspiration from crops, forests and other valuable ecosystems cannot be estimated straightforwardly as each biome type has its own biophysical response to soil moisture and fastly changing conditions of the planetary boundary layer. Although a certain consensus has been achieved on continental scale water balances (see e.g. Baumgartner and Reichel, 1975; UNESCO, 1978), spatio-temporally water flows in river basins and irrigation schemes are often only marginally known. Hence, a data crisis in land and water management persists and sound strategies to make water use more efficient are impeded by a lack of adequately quantified land surface properties, conditions and processes. Stewart et al. (1998) encapsulated the major unresolved scale issues in hydrology, and attempted to set directions how remote sensing can contribute in describing catchment scale hydrological processes better. Remote sensing from satellites has the ability to acquire data from the local scale up to the global scale.

International collaborative efforts such as IHP, IGBP, GEWEX, FAO and WMO have meanwhile been initiated to narrow the information gap with respect to land and water resources. Some global databases on for instance land cover (e.g. USGS), bio-physical properties (e.g. ISLSCP), precipitation (e.g. GPCP), and runoff (e.g. GRDC) are now established. FAO has launched several programmes (GWIS, GTIS) to combat desertification and secure food production. Aquastat is part of these activities and contains country statistics on irrigated agriculture and rural development. The area under irrigation is a continuous subject of debate as actual and design command areas may differ more than 50% and information of irrigated areas used in conventional databases is often based on design area. Despite this uncertainty, standardized data bases are important steps forward in the exchange of data among countries, or among states, sharing the same river basin. GIS systems are suitable means to integrated the data from different sources and establish the link to hydrological processes (e.g. Meijerink et al., 1994).

The major environmental concerns in the next century are 1) general water shortage, 2) water losses from irrigation systems, 3) soil degradation by human induced salinization and 4) mining of aquifers. The objective of this paper is to demonstrate that remotely sensed information can contribute to help the understanding of these major environmental concerns at the regional scale where information is not available or not accessible. The paper synthesizes methods of assessing the availability of water resources in river basins and irrigation schemes by combining remotely sensed data with distributed watershed and global hydrology models into GIS databases. A list of acronyms is provided in the annex.

2 ENVIRONMENTAL CONCERNS

2.1 General water shortage

Water resources planners need to know the total inflow and outflow in their basin to plan the allocation and distribution of water. The primary basis for all water quantities is the water balance. Available water resources depend on the difference between inflow (precipitation and snowmelt) and outflow (rainfed crop evapotranspiration, unavoidable evapotranspiration through soil and natural vegetation and surface runoff). If the demands from irrigated agriculture, domestic and industry is more than available from the sum of runoff and net groundwater recharge, water shortage persists and water allocation among competing sectors has to be based on quantitative good information.

Like the Population Action International (PAI, 1993), Seckler et al. (1998) evaluated the available water resources country by country using a water scarcity index to identify countries most vulnerable to future water deficit. One of the strenghts of their approach is that it includes a submodel on the irrigation sector that is much more thorough than any used to date in this context The indicator of water scarcity was defined as the need for development of additional water supplies for each country by the year 2025 in order to maintain approximately the same per capita water supplies for domestic and industrial uses and for food production for irrigated agriculture over the period. Regions prone to a severe water shortage lie essentially in the inter-continental line between Tunisia and Pakistan. The information required to compute global water scarcity has been pulled from 1) estimated population in 2025, 2) total annual water supply, 3) total annual water withdrawal, 4) percent of water withdraw...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Introduction/Keynote lectures
• 1 Remote sensing for sustainable development: State of the art
• 2 Implementation strategies and cost-benefit analysis
• 3 Land use and nature management
• 4 Water quality and pollution monitoring
• 5 Coastal zone management
• 6 New airborne and spaceborne techniques
• 7 Geomorphobgical hazards and floods
• 8 New processing and analysing techniques
• 9 Climate change and interaction with landuse
• 10 Sustainable development in developing countries
• 11 Monitoring environmental impact
• List of Participants
• Author index
• Colour plates