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Presentation

2nd Revision

Introduction

 
Arguments - Data Quality
Water
This study mainly uses the detailed assessment of China's water resources and demand compiled by the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP) in 1997. The ESCAP study basically brought together and evaluated information from two Chinese sources:
WB00860_.gif (262 bytes) The assessment of national water resources by the Nanjing Institute of Hydrology and Water Resources, which was conducted in 1995-1996. This was a replication of an earlier study from 1981-1985 and included detailed estimates of surface and groundwater supply, as well as water demand estimates and projections by various sectors. For its assessment, the Institute used precipitation and runoff data collected from 9,230 meteorological stations and 2,150 surface water flow stations between 1956 and 1979.
WB00860_.gif (262 bytes) Information from the Ministry of Geology, including regional hydrological mapping information for groundwater (at a scale of 1:200,000), which has been collected since the 1950s.
We have no specific information about the accuracy of these data sources. However, surface water estimates are usually more accurate than groundwater assessments. First, it is difficult to know where - and how deep - the groundwater is. Second, it is difficult to know exactly where the groundwater comes from and where it goes. While it is certainly possible to get accurate information for a small test area, it is extremely difficult to assess the amount of groundwater on a macroscale. The information must be generated using indirect, model-based methods. Therefore the groundwater estimates for China are probably rather uncertain. The accuracy of precipitation and river flow data, on the other hand, primarily depends on the number of data-collection stations and is probably quite high in China.
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Related Arguments

Water Resources:   Trends     Impact    Data Quality    Prediction Error    Intervention Possibilities    Intervention Costs

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Revision 2.0 (First revision published in 1999)  - Copyright 2011 by Gerhard K. Heilig. All rights reserved. (First revision: Copyright 1999 by IIASA.)