USACE CWMS - Minnesota River Watershed

The Corps Water Management System (CWMS) includes four interrelated models to assist with water management for the basin:

- GeoHMS (Geospatial Hydrologic Modeling Extension)
- ResSIM (Reservoir System Simulation)
- RAS (River Analysis System)
- FIA (Flood Impact Analysis)

The Minnesota River is approximately 332 miles long, and it drains a basin of about 14,751 square miles in size. The Minnesota River flows over a mantle of glacial drift from an elevation of 960 feet in the headwaters near the South Dakota border, to the confluence with the Mississippi River at an elevation of about 690 feet at Minneapolis/St. Paul. The Minnesota River is a remnant from melting glaciers after the last ice age. Originally the valley drained north; however, glacial deposits and refreezing of the area over time formed a southern outlet into what is now the Minnesota and Mississippi Rivers. Several diversion channels exist within the Minnesota River Valley and some of them are utilized in the Lac Qui Parle project as the Chippewa Diversion and Watson Sag (Minnesota NRCS November 2014).

The soil across the basin is rich in nutrients, so that 90% of land use is used for some form of agricultural production. The fertile, black, fine-grained soils and landscape are conducive to agriculture. The principal crops are wheat, barley, soybeans, sunflowers, corn, and hay. Pasture, forest, open water, and wetlands comprise most of the remaining land area.

After a long winter, temperatures typically rise above freezing across the southern basin, resulting in snowmelt and eventual runoff into the river system. As the swollen river flows north, it encounters less slope, greater amounts of snow and ice due to a colder air mass, and delayed seasonal melting. Ice jams commonly result from these factors and in turn, impedes flow and holds back excessive water. Since the river channel itself is shallow and no more than a few hundred yards at its widest point, water quickly spreads out across the surrounding landscape. The severity of spring flooding depends on several hydrometerological factors, including: freeze/melt cycle; early spring rains or late spring snow storms; snow pack depth and liquid water equivalency; frost depth; soil moisture content; river baseflows and ice conditions; and liquid precipitation from the previous year.

水体管理系统（Corps Water Management System，简称 CWMS）包含四个相互关联的模型，旨在协助该流域的水资源管理：

- 地理水文模型扩展（GeoHMS，Geospatial Hydrologic Modeling Extension）
- 水库系统模拟（ResSIM，Reservoir System Simulation）
- 河流分析系统（RAS，River Analysis System）
- 洪水影响分析（FIA，Flood Impact Analysis）

明尼苏达河全长约 332 英里，流域面积约为 14,751 平方英里。明尼苏达河从南达科他州边境附近海拔 960 英尺的源头，流经冰川漂移层，最终在明尼阿波利斯/圣保罗市与密西西比河交汇，海拔约 690 英尺。明尼苏达河是最后一次冰河时代冰川融化的遗迹。最初，该河谷向北排水；然而，随着时间的推移，冰川沉积物在该地区的重新冻结形成了一个向南的出口，即现在的明尼苏达河和密西西比河。明尼苏达河谷内存在多条分洪渠道，其中一些在拉克·基帕尔勒项目中被利用，如奇佩瓦分洪渠道和沃森萨格（美国农业部自然资源保护局，2014年11月）。

该流域的土壤富含养分，90% 的土地利用用于某种形式的农业生产。肥沃、黑色、细粒土壤和景观有利于农业发展。主要作物包括小麦、大麦、大豆、向日葵、玉米和干草。草地、森林、开阔水域和湿地占据了剩余的大部分土地。

经过漫长的冬季后，南部流域的温度通常会升高至零度以上，导致融雪并最终流入河流系统。随着膨胀的河水向北流动，它遇到更小的坡度、更多的雪和冰，这归因于较冷的空气团和季节性融化的延迟。冰坝通常由这些因素引起，进而阻碍水流并积聚过多的水分。由于河床本身较浅，最宽处不超过数百码，水迅速扩散到周围的景观中。春季洪水的严重程度取决于多个水文气象因素，包括：冻结/融化周期；早春降雨或晚春雪暴；积雪深度和液态水等效量；霜冻深度；土壤含水量；河流基流和冰况；以及前一年的液态降水量。