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GIS Plays Important Role in Managing China's Yellow River Basin
The Digital Yellow River Project
The Yellow River's destiny is tied to its geography. A dichotomy to the people who inhabit its shores, the second-largest river in China has been called both "the cradle of Chinese civilization" and "China's sorrow."
From its fertile shores, several northern Chinese civilizations sprang and prospered, but because the river flows across a large expanse of fine-grained, porous silt in the Loess Plateau, it carries a large amount of sediment. The silt deposits build up the riverbed until it is high above the surrounding plains. Even a minor rise in water level can cause the river to burst its banks. Unable to return to its breached course as the flood recedes, the river changes course and finds a new way to the sea.
Frequent devastating floods on the Yellow River, which takes its name from the yellow-colored silt it carries, account for some of the deadliest natural disasters ever recorded. The river has changed its course 26 times in 2,000 years, and hundreds of thousands of lives have been lost.
For centuries, the Chinese have tried to prevent the flooding, but the river almost always seems to have its way. As China's population grew, increased settlement on the Loess Plateau began a cycle of deforestation, overcultivation, soil erosion, and increased silt runoff that has accelerated flooding and land-use problems in the Yellow River basin. Silt buildup worsens as the river flow lessens across the floodplain, which happened as more and more river water was diverted for irrigation. Pressure to seek viable strategies for taming the river mounted.
Taming the River with Technology
The Yellow River Basin Geographical Information Center (YRBGC) began to use ArcGIS in 2001. There are now approximately 100 users. In 2002, the Chinese government, with financing from the Asian Development Bank, began construction of the Digital Yellow River project to address the ongoing challenges of the Yellow River, including flood threats, water distribution, water pollution, and soil erosion. Managed by the Yellow River Conservancy Commission, the Digital Yellow River project is still in its early stages of development, but the GIS platform construction was completed in 2009. The result is an integrated digital platform and a virtual environment where natural resource, economic, and social data is analyzed and studied. The visualization and modeling capabilities of GIS software play an important role in these efforts.
To study the natural phenomena occurring in the river, the project collects data via remote sensing and GPS verification. Data storage and processing, mathematical modeling, and support for scientific decision making are other components of the system. Powered with ArcGIS technology, Digital Yellow River is focused on forecasting rainfall and monitoring rising water levels and sources of pollution while seeking new strategies for flood prevention.
This work will help realize the project's goals of promoting economic stability in the region, securing an efficient management plan for the physical river, and advancing a fundamental change in the traditional concepts and approaches to controlling the Yellow River.
Simulating the River's Erratic Behavior
ArcGIS Desktop software, including the ArcGIS Spatial Analyst and ArcGIS 3D Analyst extensions, was implemented to develop the digital river. "GIS provides the technical support for much of the work in the digital river's development," says Gao Qingfang, department head of the Mapping Information Engineering Institute of the Yellow River Engineering Consulting Co., Ltd. "We can efficiently and accurately simulate the river's behavior and assess locations, query data, and perform analysis, which enhance our decision-making ability."
GIS is used for collecting map data and building the database for digital line graphs, document object models, and digital elevation models. With the geodatabase, digital river users can edit and query data, visualize scenarios, and print topographic and thematic maps. Data management and system maintenance have been simplified with the centralized system, and with the browser/server setup, users can easily share information by uploading or downloading files via the Internet.
Six data centers were created, including one each for flood control, water regulation, water and soil conservation, resource protection, project management, and e-government. Additionally, a mathematical simulation based on six models is under development, which will provide valuable assistance in flood forecasting, water and sediment regulation, and the construction of flood control projects. The mathematical simulation will provide the basis for the next stage, the nature-economy-ecology coupling system.
To be harnessed, the Yellow River has to be considered comprehensively. This involves studying the natural environment, as well as the economies surrounding the river. When the project is complete, the Digital Yellow River will facilitate the comparison of multiple scenarios in the context of the big picture. This will enable informed decision making regarding major infrastructure projects.
As this digital river technology matures, it will serve as a model application for other major river systems.
For more information, contact Hu Jie, Mapping Information Engineering Institute of the Yellow River Engineering Consulting Co., Ltd. (e-mail: Hujie519@163.com).