Water-saving Irrigation Technology Based On Efficient Utilization Of Water Resources In Karst Area

Guizhou province is located in the eastern part of the Yunnan-Guizhou plateau,with an average altitude of about 1,100m and a low altitude in the west and a high in the east.The special topography and geomorphology environment is characterized by,more rocks and less soil,easy to be eroded by external forces and serious soil erosion.In the development of Water-saving irrigation,there are some problems,such as insufficient capital investment,single water-saving model,low water-saving technology level,imperfect management system and imperfect legal system.After the implementation of water-saving irrigation projects,it can increase farmers'income,improve the ecological environment and promote economic development.Based on the key project of science and technology program of Guizhou Province“key technology and demonstration for the State Key Engineering Technology Research Center for Karst Rocky Desertification Rehabilitation(Qiankehe Zhongdazhuanxiang Zi[2014]6007)”,karst plateau of Bijie in Salaxi and the karst plateau canyon of the Huajiang river in Zhenfeng-guanling in Guizhou are selected as the research areas.Constructing water-saving irrigation model and technology based on efficient utilization of water resources will provide experience for the same type of karst area in the future.This paper studies from the following three aspects:1.The occurrence and utilization of water resources in karst demonstration area.Through on-the-spot investigation measure the occurrence characteristics and the development and utilization of water resources situation,ecological water requirement for vegetation analysis,as the next area irrigation utilization of water resources,water saving irrigation engineering construction to provide the reference basis.2.Constructing different water-saving irrigation technology modes under different desertification levels.We applied the theory of physical geography,karst hydrology theory,ecology theory,soil-plant-atmospheric water cycle theory,and agricultural efficient water as the theoretical basis and through experiment and demonstration research,innovative construction,which has a typical representative of water saving irrigation mode based on efficient utilization of water resources.3.We studied the new water-saving water box root irrigation technology regulation method,and explored the different effects of root irrigation and sprinkler irrigation on plant growth and soil physical properties through comparative experiments.The conclusion is as follows:1.The water resources of the salaxi demonstration area are characterized by low surface water content,high occurrence of groundwater,average annual runoff of 498.2mm,and the annual surface runoff is 42.981 million m~3.The average annual rainfall of the Salaxi demonstration area for many years is 892.5mm,The total amount of rainfall is 76.995 million m~3.And the Huangjiang demonstration area for many years is 1100mm,The total amount of rainfall is 56.782million m~3 The deep water depth of Huajiang canyon is 200-370m,the cost of water extraction is high,and it is difficult to develop and utilize the groundwater.There is a reservoir of more than1000m~2 in the area,but due to lack of maintenance in the later stage,there are problems such as wall cracking,foundation subsidence and so on.The actual capacity of water storage is less than30%,which makes the drought and water shortage deepened.2.We systematically analyzed the characteristics of water resources in Guizhou,and constructed a technical model for dry land agricultural production suitable for natural and socio-economic conditions in karst mountainous area of Guizhou.Huajiang demonstration area as a representative of the strength of karst rocky desertification the space–time location of the precipitation is not well balanced(more focused in June,July,August).The rainwater of the three small project is used as the water source,the pepper woodland in the demonstration area and the cultivated Chinese herbal medicine and pitaya and other economic crops are constructed,and the cultivation pattern of the auxiliary crops for irrigation in the Huajiang demonstration area is constructed.While in the demonstration zone model technology demonstration has been initially formed,but high and new water-saving irrigation technology penetration rate is not high,farmers'participation is low,water is hard to develop still,water-saving irrigation technology cost is higher,which can only deal with crop irrigation under drought conditions,and water saving irrigation mode need to further improve and study.3.The main point of root irrigation is to set up a special water transport tube for the most dense soil layer of plant root system,which can make the drip water directly to the best part of the crop root system effectively and improve the utilization of water.Then,according to the environment and climate of the growth and development of plants,the water and fertilizer should be fed into the root area through the multi-functional pipe in a timely and appropriate manner.Because there is dense root hair of the plant,the water and fertilizer can be imported directly to the root system of the plant,so the absorption efficiency is very high.The root irrigation is better to allow water and nutrients to stay in the soil tillage layer,reducing leakage and evaporation,but it has not yet benefited the whole Karst area,and the rest of the water saving irrigation technology still needs to be further strengthened.4.By analyzing the various indicators of soil structure,the soil bulk density increases from top to bottom,while the natural moisture content,maximum water holding rate and total porosity all decrease with the increase of depth.At the same time,this study showed that under different irrigation techniques,soil bulk density appears in order of natural>sprinkler irrigation>root irrigation,while porosity is the opposite,indicating that root irrigation is beneficial to reducing soil bulk density and enhancing soil porosity.Root irrigation can increase crop yield by more than20%,save water by 40-50%and save production cost.Fundamentally change the traditional way,which provides a new water-saving irrigation technology for rural areas,providing technical support for better field management,increases land use rate and utilization rate of water resources,with less input,more output and simple operation,and is suitable for the rich rural labor and shortage of funds.Therefore,adopting this water-saving irrigation technology not only saves water,but also has high yield and obvious economic benefit.However,the other indicators of benefit evaluation still need to be further proved by experiments.5.It is the first time to popularize and apply the water-saving irrigation model based on the efficient utilization of water resources in this region,which will help to realize the unification of economic,social and ecological benefits.The application of water-saving irrigation technology area of Salaxi in Bijie and Huajiang in Zhenfeng is about 50hm~2.On the premise of saving water,water-saving irrigation technology can basicly guarantee the farmers'income,practical strong,suitable for the actual production of local economic crops,effectively alleviate the local water resources shortage,achieve the optimization of resource allocation,for the local ecological construction and increasing farmers'income have very good help,which has great development potential.Although the Huajiang demonstration has formed the dragon fruit industry,farmers are difficult to bear the high cost of water-saving irrigation technology,also need to company and government cooperation.Thort-term economic benefit is not obvious,drip irrigation project also need the late management and maintenance,and there are problems such as waste of engineering,which needs to cause the attention of the managers.