黄土高原沟谷的发育既影响区域地表形态，又是黄土高原水土流失的重要环节。沟谷发育的不同阶段表现出不同的形态特征。沟谷形态特征与其发育历史的关系既是地貌学的基本理论问题，对黄土高原水土流失的防治也具有一定的指导意义。本文以ASTER GDEM V2 30m分辨率的DEM数据为基础，借助ArcGIS、Matlab、Excel等工具，实现了流域面积-高程曲线、沟谷条带剖面的自动生成，以及流域面积-高程积分值的自动计算。选取仕望河为例，通过面积-高程曲线、横剖面、纵剖面从定性和定量两方面刻画沟谷的形态特征，并结合野外考察所得的流域沉积结构。探讨了沟谷形态特征与演化历史间的关系。仕望河是黄河的一级支流，位于晋陕峡谷南段，黄河西岸，地处黄土高原丘陵沟壑区，是黄土高原沟谷发育的典型区域。全流域面积约为2358km2，按照A.N. Strahler的沟谷分级方法，流域内的沟谷共分为8级，即以最小沟谷做为1级仕望河干流为8级。本文重点分析了沟谷形态特征随沟谷级别的变化情况，以及不同地质条件、不同地貌部位的沟谷形态特征。最终得到以下几点认识。① 仕望河流域的地貌演化大致可分为3个阶段：唐县期侵蚀面的形成与三趾马红土的发育；沟谷的缓慢发育与阶段性下切，形成有两期宽谷台地，其中最早一期下切于早更新世初期，上覆午城黄土，第二期下切于早更新世晚期至中更新世初期，上覆离石黄土；晚更新世以来，马兰黄土堆积于平缓的塬和早期的阶地上，现代沟谷迅速下切，特别是高级别沟谷，受黄河下切影响，沟谷内存在多期侵蚀后退的裂点。由于地质条件差异，流域南北两部分沟谷的演化历史差异较大，大致以仕望河干流-西川和南川的分水岭为界，北部有厚层黄土和红土。3、4级沟谷发育其中，侵蚀速度较快。南部大面积出露基岩，沟谷发育速度缓慢。② 仕望河流域在面积-高程曲线上表现出两段式特征，即上半段呈现壮年期甚至老年期特点，下半段呈现幼年期特点；HI值在0.6左右，表现出幼年期向壮年期过渡的状态；在横剖面上表现出谷中谷；纵剖面上能看到多个裂点。说明仕望河受到黄河下切影响，存在多次下切，特别是下游地区，沟谷深切在基岩之中，裂点多，纵比降大。③ 黄河下切对仕望河流域沟谷的影响已深入6级沟谷。在纵比降上表现为8级沟谷大于7级，部分6级大于5级。5-3级沟谷的纵比降随着沟谷级别的减小而增大。在面积-高程曲线上表现出两段式特点。3、4级沟谷中仅直接注入7、8级沟谷的受到了干流快速下切的影响。这些沟谷流域面积-高程积分值较小，但纵比降较大，宽深比较小，横剖面特征较简单，基本不存在阶地或谷中谷，具有短时间快速下切的特点，且下切时间明显滞后于干流的下切。④ 流域面积-高程曲线、沟谷纵、横剖面的形态特征和定量刻画值，都能够反映沟谷的发育阶段，用于沟谷演化历史分析。沟谷发育阶段越趋向于老年期，流域面积-高程曲线下凹度越明显，HI值越小；沟谷纵剖面越平缓，甚至呈下凹型均衡剖面，纵比降越小；沟谷横剖面越呈现出宽浅形态，宽深比越大。但是沟谷发育阶段受到流域地表形态，地质条件，植被覆盖以及沟谷发育时间长短的综合影响，只有将三种形态特征描述相结合，综合分析才能够更准确地探讨沟谷演化历史。如果能够测定各级沟谷发育的绝对年龄更好。

The evolution of gullies influences the surface landscape over the Chinese Loess Plateau and induces soil loss there. Valleys show different morphological characteristics at different stages. The relationship between valley morphological characteristics and its development history is a basic theoretical problemof geomorphology. And studies on the evolution of gullies play a significant role in understanding the progress of soil erosion. In this paper, 30m-resolution DEMs, ArcGIS, Matlab and Excel are used to acquire longitudinal and transverse profiles and the hypsometric integral for each watershed of different orders in Shiwang River. Combining with basin sedimentary structure, the relationship between valley morphology and its evolution is discussed.Shiwang River is a primary tributary of the Yellow River, which is located in the southern section of Jinshaan Gorges, west of the Yellow River. The basin has an area of about 2358 km2 and is locates in the transition area from the loess tableland to the valley of the Yellow River. It is a typical area reflecting the development of loess plateau gullies. The valleys there are divided into 8 orders according to A.N. Strahler’s classification method of the drainage channels. This paper mainly analyzes how valley characteristics change with its order and the influences of geological conditions and geomorphologic positions . The results are as follows:1. Shiwang River basin is developed on Tangxian erosion surface and there are several erosion-filling cycles in the valley histories. The process can be roughly divided into three stages. The first is the formation of erosion surface and the formation of red clay. The second is the slowly cutting down of the valleys, which formed multilevel wide valley terraces. The third is Malan loess accumulation and rapid incision of modern valleys. Due to the differences of geological conditions, the evolution of valleys in the north and south parts of the basin has different features. Valleys in the north area developed faster as they incise in loess and red clay layers, especially those of the 3rd and 4th order.2. Modern valleys are formed on the basis of wide valley of maturity phase. Affected by incision of Yellow River, there are many nick points in the valley. The hypsometry curve can be divided into two parts arrording to its characteristics. The first half shows maturity and old age characters and the second half represents a valley of young stage. The hypsometric integral (HI) is around 0.6, indicating transition stage from young to mature stages. The transverse section shows valley-in-valley there.3. Most of the 6th order valleys of Shiwang River have been influenced by the incision of Yellow River. The longitudinal gradient has a decline trend as the stream order increases. But the longitudinal gradient of the 8th is greater than that of the 7th and some of the 6th order streams have a greater longitudinal gradient than the 5th streams. The hypsometry curve of 8th, 7th and some 6th valleys can be divided into two parts based on characteristics. Among the 3rd and 4th order streams, only those flowing directly into the 7th and 8th order valley have been influenced by the incision of the Yellow River. The HI and W/D ratios of these watersheds are small, but the longitudinal gradient values are great. And their transverse profiles are relatively simple. All these characteristics show that the 3rd and 4th order valleys were delayed from the incision of the truck of Shiwang River.4. The Hypsometric Curves, Longitudinal and Transverse Profiles can reflect the evolution stage of valleys. But the evolution of valleys is influenced by many factors. Only by taking all of the three kinds of morphological characteristics into consideration can the analysis of evolution history be more accurately.