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Hydrology

This  section was designed to provide information on the fundamentals of stormwater management. In this section, one will be able to learn the essentials concepts needed to understand and implement SWPPPs (Stormwater Pollution Prevention Plan) and BMPs (Best Management Practices).

The NPDES Permit Program is another topic covered under this section, and it is one of the main driving forces behind the majority of the mandated state and federal regulations. Under the NPDES Permit Program, stormwater discharges are considered point sources and operators of these sources may be required to receive an NPDES permit before they can discharge.

This NPDES Program was created through the authorities granted in The Clean Water Act, which was enacted by Congress and signed by the President to establish such environmental programs. The basis behind this act is to protect the Nation's waters and directs EPA to develop, implement, and enforce regulations consistent with this law.


Construction Activities

BMP Handbook

Click here to learn more about the various State Regulations concerning Stormwater Management

Design Guidance

Final Stabilization

Click here to learn more about the various Stormwater Rules and Notices presented by the EPA.

Regulated MS4s

Site Inspections

Click here to learn more about the various Federal Acts that may impact NPDES permitting.


Simply put, hydrology is the study of water. It is the evaulation of the occurrence of water, how it is distributed throughout the planet, water particle movement as it interacts amongst other particles and obstacles, and the control, management and utilization of  life’s most essential resource, water.

Hydrology has produced many of the key concepts that directly impact not only stormwater but many other fields. Some examples of these are the hydrologic cycle (the water cycle), hydrographs and drainage basin management.

 

The Hydrologic Cycle 

ddThe hydrologic cycle is the reoccurring movement of water through the earth’s atmosphere, its surface (both above and below), through steams, rivers, and seas, and finally is purified as it reenters the atmosphere through evaporation, allowing the cycle to begin again.

As the Sun heats the oceans and seas, water vapors rises up into the atmosphere through a phenomenon known as evaporation.  Once in the atmosphere, these water vapor particles collide, form clouds, and condense as air currents disperse them throughout the world. Under saturated circumstances these vapor particles condense and fall back to the ground in various forms including rain, snow and hail.

Portions of the condensed water will fall back into rivers, lakes and seas but a significant amount will fall onto the ground, providing water to the flora and fauna of the world. Much of the water that hits the surface will infiltrate into the ground, recharging aquifers. The remainder will flow over the ground into lakes, streams and oceans. The latter is known as surface water runoff or stormwater runoff.

There are multiple pathways in which water may take as it progresses through the hydrologic cycle, a process that can take days or millions of years (if water becomes stored in polar ice caps). Whatever the case, people continue to tap the hydrologic cycle for personal use.

Stormwater Basic Information Page

Hydrology and Stormwater

Understanding hydrology is an essential requirement when it comes to designing and implementing stormwater management plans. It is through the use of hydrologic concepts, i.e. hydrographs, that designers are able to model storm events and analyze how much stormwater runoff will be released downstream depending on land usage, stormwater controls, and rain intensity.For more information on stormwater modeling please visit the links below.

Hydrographs

 


Bureau of Water . Phone: (803) 898-4300 . Fax: (803) 898-3795 . Contact Us