Benefits and ecological risks of Gully Reclamation Project in Yuanmou Dry-hot Valley region

Abstract: The Yuanmou Dry-hot Valley of the Jinsha River is an ecologically fragile region with severe gully erosion in southwest China. Gullies, with the density of 3 to 5 km/km2, erode the farmland and form the erosion badlands, accounting for approximately 70% of the total area and inducing rapid land degradation. However, this valley features extremely hot weather, with annual average temperature of 21.7 °C and annual sunshine of 2 550-2 744 h. The abundant sunshine and heat resources make this valley being a large "natural greenhouse", which is very favorable for developing off-season agriculture. The vegetable and fruit plantation in this valley have high output and quality. Since 2010, a new land management model to reuse the gully erosion badlands has been carried out in this area, namely the Gully Reclamation Project. This project has played an important role in increasing the cultivated land resources and economic returns, however, with the project implementation, the potential ecological risks cannot be ignored. In this study, visual interpretation methods were employed to identify the area of the Gully Reclamation Projects. Then, we conducted field surveys in 6 villages with the greater project distribution, Laocheng, Pingtian, Huangguayuan, Xinhua, Wumao, and Yuanma. And ultimately, we visited a number of farmer households, and 8 typical projects were selected to analyze the technology and operation modes, and output benefit of this land management project. The potential ecological risks during the project implementation were also discussed. The results showed that the Gully Reclamation Project with the main investors of enterprisers and local farmers significantly improved the land resource utilization efficiency in the area. From 2010 to 2018, the project completed new arable land a total area of more than 6700 hm2, accounting for about 5% of the area of the dry-hot valley. Meanwhile, the project brought huge economic benefits for enterprisers and local farmers. The total land construction investment was 33000-180000 yuan/hm2, with an average of 106 500 yuan/hm2. Taking the mostly planted grapes and tomatoes as examples, the total annual output was 1.4 to 12.7 times and 1.3 to 6.3 times of the average land construction investment, respectively. However, with the implementation of the project, there are also several potential ecological risks, such as the rill erosion in terrace slopes, the imbalance of water resources utilization in new land, and the threat to water safety caused by the massive application of pesticides and fertilizers. In general, the Gully Reclamation Project is a non-governmental organized and successful land management. However, it is of great significance to strengthen the scientific monitoring and researching on the specific ecological benefits and potential ecological risks in the future. This can provide a theoretical basis for the scientific implementation of the project and the sustainable development of economic, ecological and social benefits.