Starting with the water system is the most direct and effective way to understand the Lalu wetland. At first, in addition to the natural rain and snow, the water source of Bacon Wuzi ravine, and now the "wetland spring eye" on the east side of Luding North Road, the main source of the Lalu wetland water system is the quicksand river water from the confluence of Niangge gully and underground gully. Since the state of "self-flowing and scattered flow" in the mouth of the Liusha River changed in the 1970s, the Liusha River has become stable and sufficient due to the constraints of canals. However, since 1980' s, a large number of immigrants, temporary sheds and waste accumulation have blocked the entrance of Liusha River into the wetland. From the introduction of Solang Pincuo, who has been engaged in the observation and reporting of Lalu wetland for a long time, we know that another consequence of the quarry is that the beautiful black-necked crane once abandoned the wetland with a huge explosion. Fortunately, after 2000, with the government closing the quarry and closing the mountain for greening, the Liusha River returned to the normal state of supplying water to the wetland.

Since 1990, with the acceleration of the construction of Lhasa main canal, the water supply source of Lalu wetland has added new strength. This main canal originated from Haiyun Villa in Jinna Village, Dongtou, Lhasa.

Near the origin, a tributary along the north side of Lhasa River is called Nangan Canal, and a tributary along the foot of the mountain divides into two at a prominent mountain pass in Zangre Township. Among them, the one that goes north along the mountain, passes through Lhasa Racecourse, and then goes northwest is called the North Main Canal, and finally it is adjacent to and parallel to the Liushahe Main Canal at the eastern end of Barku Village, forming another water source in the northeast corner of Lalu Wetland. This area is the area with the richest vegetation and the densest water network around Lalu Wetland.

Another canal due west is the trunk canal, which passes through the freight station in the eastern suburb, then flows west next to Dangrang West Road and enters the middle section of Dangrang West Road, and the trunk canal forms Larush.

The southern edge of this land. However, the middle trunk canal, which integrates many tasks such as farmland irrigation, urban sewage discharge and green belt, and water supply in Lalu wetland, did not realize the function of water supply for Lalu wetland at first because of its relatively low terrain and unstable dam, but accelerated the infiltration and discharge of wetland water. After strengthening the canal dam, building additional sluices in sections and widening the water inlet of the wetland, the underground pipe network for sewage discharge in the northern suburbs was basically realized, and the original intention of supplying water to the Lalu wetland by the central main canal was truly realized.

balance

Choose a sunny day in July in Lhasa, walk west along Dangrang West Road (also known as the Second Ring Road), and you will see a sluice on the main canal less than 100 meters after passing the Lalu neighborhood Committee. In order to store high water level in rainy season and inject it into the entrance of the southeast corner of Lalu Wetland, this sluice is usually closed. From the water intake through an arch bridge (commonly known as Jigong Bridge) to the next closed sluice, there are obviously a lot of foreign objects in the full middle trunk canal.