According to the relevant achievements in the “Comprehensive Water Resources Planning of Lijiang City”, and in combination with other relevant data and the new changes in the future water supply situation, the original forecast results of supply and demand and the results of water resources allocation were reviewed. After review, the variation trend of various economic indicators in recent years is basically consistent with the calculation of water demand forecast in the “Comprehensive Water Resources Plan of Lijiang City”. Therefore, the forecast results of supply and demand in 2030 and the allocation results are predicted by referring to the results in the “Comprehensive Water Resources Plan of Lijiang City”. According to the forecast, the Wulang River Basin will have an average annual water demand of 103.1 million m³, a water supply of 101.47 million m³ and a water shortage of 1.63 million m³ in 2030, with a water shortage rate of 1.6%. The results of supply and demand analysis under different frequencies ( Table 1 ) and the results of water resources allocation ( Table 2 ).

Note: unit: ten thousand cubic meters.

Note: unit: ten thousand cubic meters.

According to the “Opinions of the People’s Government of Lijiang on Implementing the Strictest Water Resources Management System” (Li Political Office issued No. 53 [2014]), “The Notice of the People’s Government of Lijiang on Printing and Distributing the Assessment Methods for Implementing the Strictest Water Resources Management System in Lijiang” (Li Political Office issued No. 79 [2014]), and “The Office of the Leading Group of the Assessment for Implementing the Strictest Water Resources Management System in Lijiang Letter on the Issuance of the ‘Three Red Lines’ Control Indicators for Implementing the Strictest Water Resources Management System during the 13th Five-Year Plan Period”. The Lijiang City puts forward the 2020 and 2030 Total Water Consumption Control Index (TWCCI) for each district and county, among which the TWCCI for Yongsheng County and Ninglang County ( Table 3 ).

Note: unit: ten thousand cubic meters.

Yongsheng County and Ninglang County haven’t yet put forward the decomposition results of the TWCCI decomposition in the Wulang River Basin. Based on the total water use indexes of Yongsheng County and Ninglang County, combined with the “Comprehensive Water Resources Plan of Lijiang City”, and considering the water demand of each county under the premise of not breaking the regional total water use control, The total water use indexes of Yongsheng County and Ninglang County are decomposed into the Wulang River Basin.

Considering that the allocated water supply of some districts and counties determined in the “Comprehensive Water Resources Plan of Lijiang City” and the “Comprehensive Plan of Wulang River Basin of Lijiang City of Yunnan Province” exceeds the TWCCI divided into each district and county by Lijiang City, the TWCCI of each district and county shall be decomposed according to the proportion of the planned allocated water supply of Wulang River Basin in the comprehensive water resources plan of each district and county. The decomposition results of the TWCCI for Yongsheng County and Ninglang County are obtained. Namely, the TWCCI for Wulang River Basin in Yongsheng County and the TWCCI for Wulang River Basin in Ninglang County ( Table 4 ) in 2030 are 78.48 million m³ and 13.78 million m³.

Note: unit: ten thousand cubic meters.

This water allocation plan takes Wulang River Basin as the object, based on the results of TWCCI of Yongsheng County and Ninglang County, and considers the water demand of each county administrative region to decompose the TWCCI of Wulang River Basin. Combined with the configuration results of the “Comprehensive Water Resources Planning of Lijiang City” and the “Comprehensive Plan of Wulang River Basin of Lijiang City, Yunnan Province”. The results of water supply allocation plan in 2030 within the distribution range will be finalized ( Table 5 ).

In Wulang River Basin, there are Zong Guan Tian Hydrology Station (National Basic Hydrology Station) and Liangguan, Songping, Machangping, Bai Caofao, Chuma Ping, Muler Ping, Zhanhe and other rain measuring stations (National basic rainfall measuring stations), among which Zong Guan Tian hydrology Station is located in the mainstream of Wulang River.

Note: unit: ten thousand cubic meters.

According to the requirements of water resources management in the basin, the control sections were selected according to different types, such as important water system nodes, cross-administrative control sections, important water conservancy projects and important cities. In order to facilitate the supervision and inspection of water consumption in various regions in the basin, the hydrology station in the main field was selected as the main control section of the Wulang River Basin in combination with the layout of hydrology station network. The Shutian Hydrology Station is the only hydrology station in Wulang River Basin. It was established by Yunnan Provincial Bureau of Hydrology and Water Resources on January 1, 1959. The station is located in Shutian Village, Sanchuan Town, Yongsheng County, Lijiang City, Yunnan Province. The basic situation of control section in Zongguantian ( Table 6 ).

According to the “Code for Calculation of Water Demand of River and Lake Ecological Environment”(SLT712-2021), for rivers with a long series of hydrological data, the ecological base flow can be calculated by Qp and Tennant, and the ecological base flow in Zongguantian section of control can be calculated by two methods: 90% guarantee rate of the driest monthly average flow and 10% of the average annual flow.

The 2030 allocated water volume of Wulang River Basin involved in Yongsheng County and Ninglang County is divided into each water source by referring to the proportion of water supply from each water source in the multi-year average allocation results of the “Comprehensive Water Resources Plan of Lijiang City” and considering the water supply situation and the requirements of water resource conservation and protection. The water allocation plan of each county is reasonably determined to obtain the water share of surface water, groundwater and other water under the multi-year average, 50%, 75% and 95% inflow frequency of each county [4] - [6] .

According to the preliminary results of the groundwater control index plan of Lijiang City, the groundwater control index of Yongsheng County in 2030 is 4.6 million m³, which can be converted to 1.4 million m³ for the Wulang River Basin involved. The groundwater allocation amount in the water resources allocation scheme is 830,000 m³, which does not exceed the requirements of the groundwater control index. Therefore, the groundwater supply in Wulang River Basin involved in Yongsheng County in 2030 will be based on the results of the water resources allocation scheme, namely 830,000 m³.

According to the preliminary results of the groundwater management indicator scheme for Lijiang City, the groundwater management indicator for Ninglang County will be 2 million m³ by 2030, which translates to 310,000 m³ for the Wulang River Basin involved. The groundwater allocation amount in the water resources allocation scheme is 1.1 million m³, which exceeds the requirements of the groundwater control index. Therefore, the 2030 groundwater supply of Wulang River Basin involved in Ninglang County is translated by the groundwater control index, which is 310,000 m³.

The water supply from other sources is the result of the water resource allocation scheme. Namely, the Wulang River Basin involved by Yongsheng County and Ninglang County will have 750,000 m³ and 440,000 m³ respectively in 2030.

Finally, the configuration results of surface water, groundwater, and other water sources in the Wulang River Basin that are involved in Yongsheng County and Ninglang County are obtained ( Table 7 ).

Note: unit: ten thousand cubic meters.

In this paper, the 31-year series average of surface runoff of the control section of the Zongguantian hydrological station is analyzed. The selection of typical years is based on the empirical frequency of the annual runoff series of the hydrological station, and the years with frequencies around 50%, 75% and 95% are selected as the representative years. According to the hydrology station of Zongguantian, the average annual surface runoff ( Table 8 ) is 861.52 million m³.

Note: unit: ten thousand cubic meters.

Considering that Wulang River Basin has a low degree of exploitation and utilization, little water demand for economic and social development, and a high degree of river ecological flow guarantee, the ecological base flow of the main field hydrology station section of Wulang River Basin is determined by 90% of the dry month ( Table 9 ), that is, 3.92 m³/s. If the natural runoff is less than the ecological discharge, the natural runoff shall be discharged.

Note: unit: ten thousand cubic meters.

In consideration of the ecological and downstream water demand for living, production and shipping, the minimum lower discharge index of the control section of the Wulang River Basin is determined by comprehensively considering the existing achievements. The specific achievements ( Table 10 ).

Note: unit: ten thousand cubic meters.

According to the selected control section, the water discharge index of each section is determined by deducting the surface water consumption above the section by the surface runoff at each frequency, and taking into account the water transferred in, transferred out and the storage of the main control project. The calculation formula is shown in Equation (1).

$W_D=W_M+W_{\text{Pin}}-W_I-W_{\text{Pout}}-\Delta W$ (1)

where:

$W_D$: The amount of downward discharge in section;

$W_M$: Section measured runoff;

$W_I$: Increased surface water consumption above section;

$W_{\text{Pin}}$: Plan to transfer water volume above section;

$W_{\text{Pout}}$: Plan to transfer water from the above section;

$\Delta W$: Water. Storage variables of important control projects above the section (increase is positive, decrease is negative).

Under the multi-year average of 2030, P = 50%, P = 75% and P = 95%, the discharge water of Wulang River Basin at different frequencies ( Table 11 ).

Note: unit: ten thousand cubic meters.