不同土地利用模式下红壤坡地雨水产流与结构拟合

Rainwater runoff transportation on different underlying surface and system construction in hilly region of red soil

模拟主要利用方式构建的垫面为主导因子,采用径流场实测方法,通过4年(1998—2001年)实地观测试验,剖析不同下垫面对雨水地表径流的影响。研究表明:降雨和下垫面是影响地表径流特征的主导因素;年降雨量与地表径流量和系统水土流失量呈正相关。不同垫面地表径流产量有显著性差异;雨水径流过程的土壤和养分流失有相似的表现。在假定雨水年份的基础上,提出"利用坡地集雨优势,构建与单元生态系统水循环平衡相适应的坡地农林复合生态系统,通过水平衡生态建设来维系生态系统的水分平衡"观点。以集雨区水量平衡为基础,从分析坡地水文过程入手,以坡地不同生态系统雨水分配、降雨过程地表径流产量、径流过程的土壤及养分流失量为参数,以生产灌溉对集雨的要求、坡地不同生态系统对雨水侵蚀的承载力、坡地雨水运移过程对环境和区域洪涝灾害的影响为约束条件,拟合出红壤丘岗坡地农林复合生态系统构建适宜的土地利用结构:人工林占30%,人工草地占15%,果药茶园占30%,耕地占20%,自然保护区占5%。该用地比例(结构)既满足于地貌单元(集雨区)生态系统利用坡地集雨维持系统水循环平衡的要求,也满足于坡地农林复合生态系统的可持续性保护的要求。

The influence of different underlying surface on rainwater runoffwas studied through 4-year＇s spot observation from 1998 to 2001. The leading factors were considered in this experiment which simulated the local inain land use patterns through the construction of runoff plots. Result showed that the temporal distribution and rainfall intensity were the main factors influencing surface runoff characteristics. Surface runoff, soil and water loss, and subsequent soil nutrient loss were all positively correlated with precipitation. Among the seven types of underlying surface, there were significant differences in surface runoff, i.e. farmland 〉 tea plantation 〉pine woodland 〉persimmon orchard 〉orange orchard 〉 natural degraded grassland 〉natural recovered shrub land. According to the indexes of precipitation, a viewpoint was presented in this paper that multi-functional agro-forest should be constructed through making use of slope rainwater, which is adaptable to taking advantage of gathering rainfall water in slope ecosystems, and benefit to water cycling in unit ecosystems. The water balance of ecosystems can be maintained through ecological construction. Based on the water balance in a catchments and taking account of the main parameters such as rainfall distribution, runoff amount, and soil and water loss, a reasonable land use structure was fitted in the hilly land of red soil with multiplex agro-forest ecosystem. The proportion is 30% for forestations, 15% for grassland, 30% for tea plantation, 20% for cropland, and 5% for natural reserve area. Besides, This proportion can both satisfy the request of water cycling for the ecosystems in a geolnorphic unit i.e. catch- inents, which inainly rely on water-gathering using slope systems, and meet the sustainable protection for multiplex agro-forest ecosystems.