Method for flood control

Abstract

A dynamic fluid flow control structure is provided that allows precise control over fluid flow using a series of two or more orifices, at least one of which may be reconfigured to change its flow characteristics. A flood control system and a flood control process are provided that emulate a preset discharge profile over time. Some versions of the structure, process, and system can be used to provide controlled storm discharge patterns in a developed area that emulate the natural pre-development discharge patterns.

I claim: 
     
         1 . A method of mimicking a pre-development response to a storm event in a developed watershed at an outlet point, the method comprising:
 (a) providing a flow control structure at the outlet point, wherein the flow control structure can be reconfigured to control the rate of flow at the outlet point;   (b) measuring a first rainfall amount at a first time;   (c) calculating a first direct runoff hydrograph based on the first rainfall amount and based on characteristics of the watershed prior to development;   (d) measuring a second rainfall amount at a second time;   (e) calculating a second direct runoff hydrograph based on the second rainfall amount and based on characteristics of the watershed prior to development;   (f) calculating a predevelopment total runoff hydrograph by summing at least the first direct runoff hydrograph and the second direct runoff hydrograph, wherein the total runoff hydrograph is a line having exactly one flow rate value for each time value; and   (g) reconfiguring the flow control structure at a third time to provide a rate of flow about equal to the flow rate value on the predevelopment total runoff hydrograph corresponding to the third time.   
     
     
         2 . The process of  claim 1  wherein the predevelopment total runoff hydrograph emulates the relationship between rainfall and rate of volumetric discharge as observed in the developed watershed prior to development. 
     
     
         3 . A machine-readable data storage device comprising a computer program which, when read by a computing device, causes the computing device to perform the process of  claim 1 . 
     
     
         4 . A method of mimicking a pre-development response to a storm event in a developed watershed at an outlet point, the method comprising:
 (a) providing a flow control structure at the outlet point, wherein the flow control structure can be reconfigured to control the rate of flow at the outlet point;   (b) measuring a first rainfall amount at a first time;   (c) calculating a first direct runoff volume based on the first rainfall amount and based on characteristics of the watershed prior to development;   (d) multiplying the first direct runoff volume to the first ordinate of a unit hydrograph to obtain a first predeveloped total runoff hydrograph value;   (e) reconfiguring the flow control structure at a first time to provide a rate of flow about equal to the flow rate value on the predevelopment total runoff hydrograph corresponding to the first time;   (f) measuring a second rainfall amount at a second time;   (g) calculating a direct runoff volume based on the second rainfall amount and based on characteristics of the watershed prior to development;   (h) multiplying the second direct runoff volume to the first ordinate of a unit hydrograph to obtain a first direct unit hydrograph value for the second time;   (i) multiplying the first direct runoff volume to the second time ordinate of the unit hydrograph to obtain a second direct unit hydrograph value for the second time;   (j) calculating a predevelopment total runoff hydrograph by summing at least the first direct runoff hydrograph value and the second direct unit runoff hydrograph value at the second time, wherein the total runoff hydrograph is a line having exactly one flow rate value for each time value; and   (k) reconfiguring the flow control structure at a second time to provide a rate of flow about equal to the flow rate value on the predevelopment total runoff hydrograph corresponding to the second time.   
     
     
         5 . The process of  claim 4  wherein the predevelopment total runoff hydrograph emulates the relationship between rainfall and rate of volumetric discharge as observed in the developed watershed prior to development. 
     
     
         6 . A machine-readable data storage device comprising a computer program which, when read by a computing device, causes the computing device to perform the process of  claim 4 .