Water Consumption in Ningxia Reach of the Yellow River since Integrated Regulation

The annual allocation, inter-annual variation and relation of water diversion and recession are analyzed in Ningxia reach of the Yellow River main stream from 1999 to 2012. Water consumption in Ningxia reach was calculated by water diversion-recession method and water balance method. The average value of water diversion-recession method is 3.264 billion m and annual variation is relatively steady. The result of water balance method is 3.937 billion m and annual variation is obvious. It is suggested that strengthen verification of entrances and monitoring of water diversion and recession.


Background
The Yellow River water regulation implements double control principles, i.e. total water consumption and discharge of control section [1]. Water diversion of the Yellow River main stream in Ningxia reach is mainly from irrigation, industry and urban living water, and water recession mainly related to agricultural irrigation and process structure of industrial water. In recent years, the complexity of water diversion and recession was increased due to the development of agricultural irrigation rule, water-saving transformation, water recession reuse, and

Basic Data
Integrated water resources regulation of Yellow River began in March 1999 [2], so the year from 1999 to 2012 is selected as study period. Water diversion-recession data are from monthly report of water diversion project which have license issued by Yellow River Conservancy Commission. Hydrology data of different time scale in main stream and tributaries of Yellow River are from Yellow River basin hydrological almanac [3].

Method of Water Diversion and Recession
For particular river section, water consumption is the difference of water diversion and water recession, based on the calculation of observed water diversion and water recession.
where: W C , water consumption; W D , water diversion; W R , water recession.
The accuracy of the method result depends on the accuracy of the data of water diversion and water recession.

Method of Water Balance
Water balance method is based on the observed data of hydrological station, and evaporation and leakage loss were deducted from the difference of upper and lower section discharge, according to the principle of water balance [4] [5]. The equation is as follows: where: W U , upper reach inflow; W L , lower reach effluent; W S , controlled water quantity; W UC , uncontrolled water quantity; W E , water surface evaporation; W L , section channel leakage; W C , industrial and agricultural water consumption.
According to features of the Yellow River, the interval water consumption of industry and agriculture has its special definition. Water consumption of agricultural irrigation refers to the water which can't return to the Yellow River due to evaporation and leakage in irrigation process of farmland, grassland, forest and so on. Water consumption of industrial and urban domestic includes user consumption and drainage loss, i.e. the difference of water diversion and waste water into rivers.
where: W E , net evaporation, 10 8 m 3 ; E, mean annual evaporation, mm; a, conversion coefficient of different evaporating dish; P, average rainfall, mm; A, water surface area, km 2 .

Entrance Number of Water Diversion-Recession
There are fourteen water diversion entrances in Ningxia Hui Autonomous Region approved by Yellow River Conservancy Commission. Among them, eight for agriculture, three for industry, two for hydropower and one for resident life [6].
In order to reflect the real status of water diversion and recession, remote sensing images of thirty meters resolution in Google earth were applied, and 140 water entrances and the latitude and longitude were identified from Xiaheyan to Shizuishan.

Analysis of Water Diversion
The Ningxia reach is divided into four parts, i.e. upper

Analysis of Water Recession
Water recession in Ningxia reach is as follows: no water recession in Meiliqu upper Xiaheyan, water recession in Xiaheyan~Qingtongxia is the same of WNIA and in Qingtongxia~Shizuishan is the same of QTXIA, and no water recession lower Shizuishan.

S. Y. Jin et al. World Journal of Engineering and Technology
Water recession in WNIA and QTXIA is mainly occurred in May to August and November, which related to water diversion in irrigation area. Unlike variety of annual water diversion, water recession occurred in the whole year.
The average annual water recession in WNIA is 0.79 billion m 3 , which showed obvious yearly change. The lowest is 0.627 billion m 3

Relationship of Water Diversion and Water Recession
The average ratio of water recession and water diversion in WNIA is 0.46, the maximum is 0.64 and the minimum is 0.35, shown in Figure 1. There is no obvious relationship between water recession and diversion, shown in Figure 2.
The average ratio of water recession and water diversion in QTXIA is 0.54, the maximum is 0.63 and the minimum is 0.46, shown in Figure 3. The relationship between water recession and diversion is very well-larger water diversion larger water recession, shown in Figure 4.

Results of Water Diversion-Recession Method
Water diversion-recession in Ningxia irrigation area controlled better. Seventeen monitoring sites of water diversion and pumping diversion control more than 98% of the total irrigation area water diversion amount. Through various means such as measure, survey, investigation and so on, water recession was controlled over 90% of the whole irrigation area [8] [9].
(1) Water diversion. There is one water diversion entrance locates upper Xiaheyan, six locate in Xiaheyan~Qingtongxia, two locate between Qingtongxia and Shizuishan, three locate lower Shizuishan. The sum of each river channel is the total water diversion.

Comparison of the Two Methods
Through comparison of water consumption calculation results by the two methods, we can see water consumption calculated by water balance method is large than that calculated by water diversion-recession method. The mean water consumption calculated by water balance method is 3.937 billion m 3 , while by water diversion-recession method is 3.264 billion m 3 , and the difference is 0.673 billion m 3 .

1) Water diversion in Ningxia reach is mainly occurred in April to August and
November, and the mean water diversion in 1999-2012 is 6.81 billion m 3 . The mean value in WNIA is 1.73 billion m 3 , which showed slowly increasing trend; the mean value in QTXIA is 5.08 billion m 3 , which showed slowly decreasing trend.
2) Water recession in Ningxia reach is mainly occurred in May to August and November, and mean water diversion in 1999-2012 is 3.542 billion m 3 . The mean value in WNIA is 0.79 billion m 3 , which showed obvious yearly change; the mean value in QTXIA is 2.752 billion m 3 , which showed slowly decreasing trend.
3) The average ratio of water recession-diversion in WNIA is 0.46, and there is no obvious relationship between water recession-diversion. The mean ratio is S. Y. Jin et al.