Background Information
What is a Watershed?
Every place on the earth is a part of a watershed. Homes, farms, ranches, forests, small towns, big cities and more can make up watersheds. The concept of watershed is an important one because it pertains to everyone. No matter where someone lives, they live in a watershed. A watershed, also referred to as drainage basin or a catchment, is defined as an area of land that intercepts and drains precipitation through a particular river system or group of river systems. In other words, it is a region of interconnected rivers and streams which function as a system for water transport. Watersheds come in all shapes and sizes - some are millions of square miles while others are just a few acres. Some cross county, state, and even international borders. There are many living and non-living things in watersheds. Watersheds are constantly changing.
Watersheds are dynamic and unique places. They are a complex web of natural resources - soil, water, air, plants and animals. Yet, everyday activities can impact these resources, ultimately impacting our well-being and economic livelihood. Healthy watersheds are vital for a healthy environment and economy. Our watersheds provide water for drinking, irrigation and industry. Many people also enjoy lakes and streams for their beauty and for boating, fishing and swimming. Wildlife also needs healthy watersheds for food and shelter. What we do in the watershed has far reaching effects. As more people move into a watershed, more homes are built and more resources used. Human uses of the land change the quality and quantity of water and can affect the species diversity. Non-native plants can begin to invade and outcompete some native species.
A watershed is comprised of the land area that drains into a body of water. An example might be to use a bowl to represent a watershed. The rim of the bowl represents the highest peaks of the mountains surrounding a valley with a river below, the bottom of the bowl. The inner walls of the bowl represent all of the smaller hills and mountains in the valley. Only water that falls on the rim and the inner walls of the bowl will enter the river. All other water that falls outside of the bowl rim and inner walls will flow in another direction, into a different watershed. Water that is polluted anywhere in the watershed, even if it is hundreds of miles away, will eventually flow into the estuary, the tidal mouth of the river or stream. To keep the water in the estuary clean, it is essential for the water in the transport system to also be kept clean, ultimately maintaining a healthy environment for the plants and animals that live there.
Gravity and topography are the two major factors that define a watershed. Gravity is the force of nature that pulls all water downhill. Topography describes the form of the land: the hills, valleys and other features that influence where and how water will flow. After saturating the ground, rain or meltwater trickles downhill and eventually flows into streams. These then merge into rivers that finally flow into the ocean. Gravity and topography help define these channels of water from the tiny to the huge and cause them to join together into stream networks. These water-flow structures frequently resemble the branching pattern of trees or blood vessels.
The benefits and services provided by healthy watersheds are numerous and include reduced vulnerability to invasive species, climate change, and future land use changes. Healthy watersheds with natural land cover and soil resources also provide vast carbon storage capabilities, offsetting greenhouse gas emissions. Healthy watersheds also provide habitat for fish, amphibians, birds, and insects and stream corridors which provide a key connection across the landscape for animals and birds. Aside from the reduced costs of restoring impaired waters, there are many other economic benefits to protecting and conserving healthy watersheds. Healthy watersheds preserve recreation opportunities such as fishing and water-related recreation (e.g. boating) and contribute to tourism (e.g., hiking and birding). Vulnerability to floods, fires, and other natural disasters is minimized, thereby reducing costs to communities.
Comments: