黄土丘陵沟壑区沟道土地整治工程原理与设计技术

黄土高原实施退耕还林还草工程之后,凭借沟道土地整治工程的推进,实现了坡面与沟道协同治理、生态保护与农业生产协调发展的"双赢"目标。论文基于复杂流域系统的视角,探讨了黄土丘陵沟壑区沟道土地整治工程原理与设计技术,提出了沟道土地整治应以增良田、保生态、惠民生为主题,以景观协调、结构稳固、利用持续、功能高效为理念,强调山上退耕还林、山下治沟造地,治沟保生态、造地惠民生。制定了沟道土地整治分区、分类标准及技术要点,划定了修复整治型、配套完善型、开发补充型、综合治理型等4种工程建设类型,创建了"干-支-毛"分层防控、"渠-堤-坝"系统配套、"乔-灌-草"科学搭配的增强型沟道整治工程技术体系。这些原理与技术近3年来应用于延安治沟造地土地整治重大工程实践,取得了明显成效。为进一步发挥土地整治工程的综合效益,论文梳理提出了加快推进新型农村社区化与民居安置、城乡服务均等化与设施配套、现代农业产业化与基地建设、农村土地资产化与制度创新等4大配套工程建设及对策建议。

Engineering philosophy and design scheme of gullyland consolidation in Loess Plateau

Loess Plateau used to be the area with the most serious erosion in China even world. Erosion area in Loess Plateau was up to 454 000 km2, accounting for 70% of the total area in the 1990s. Extremely intensive erosion area with erosion modulus more than 8 000 t/(km2·a) was up to 85 000 km2, accounting for 64% of the similar areas in China. Severe erosion area with erosion modulus more than 15 000 t/(km2·a) was up to 37 000 km2, accounting for 89% of the similar areas in China. Since 1998, Grain-for-Green Project has been implemented in the Loess Plateau. With the advancement of Grain-for-Green Project, forested land and grassland increase, and farmland decreases. Besides, as the population grows, Grain-for-Green Project has negative effects on grain production in some regions, and the population-grain conflict is intensified. In Yan''an, Shaanxi Province, farmland decreased by 74 000 hm2, grain production decreased by 156 000 t, and per capita grain production decreased by 132 kg with an increase of the residential population of 260 000 compared with those prior to the implementation of the project. With the further intensification of the conflict between population and grain, the demand for new agricultural production space is increasing. After decades of implementing Grain-for-Green, the vegetation cover rate increases and the erosion decreases greatly, which creates preconditions for gully land consolidation. Local initiatives of gully land consolidation since 2012 have achieved initial success. Gully land consolidation creates new space for agricultural and rural development. But how to design and plan the gully land consolidation engineering at a large scale and thus make it be approved by the central government needs systematic thinking and research. Taking Yan''an City, Shaanxi Province as a case study, this paper introduces the basic concepts of the gully land consolidation and its enhanced design in the Loess Plateau. Taking "farmland increasement, ecological protection, people''s livelihood guarantee" as the theme, and "landscape coordination, structure stability, sustainable land use, effective function" as the concepts, the project highlights the land use zoning, which can be described in detail as "returning farmland to forest on the mountain, consolidating gully to farmland in the valley", and put the emphasis on protecting ecological environment and benefiting local residents'' livelihood. In the step of planning and design, the zoning, classification standards and key techniques of gully land consolidation are identified, and 4 project construction types are proposed, which are restoration-type consolidation, facilities-type consolidation, exploitation- type consolidation, and comprehensive management-type consolidation. Furthermore, the enhanced consolidation technology system is also created, which involves "mainstream-tributary-capillary flow" tiered prevention and control technology, "canal-embankment-dam" matching system, and "tree-shrub-grass" scientific collocation. Since the implementation of the major project of more than 2 years, it has generated economic, social and ecological benefits to some extent. To further exert the project''s comprehensive benefits, the next 4 major projects need be adopted, namely new rural communities and residential resettlement project, urban and rural equalization of services and service facilities engineering, modern agriculture industrialization base construction, and rural land capitalization and land system innovation.