153 



(1) As a preliminary map for planning extensive drainage projects, 

 showing areas of catchment for water supply, sites for reservoirs, routes 

 of canals, etc. 



(2) For laying out highways, electric roads, railroads, aqueducts and 

 sewerage systems, thus saving the cost of preliminary surveys. 



(3) In improving rivers and smaller waterways. 



(4) In determining and classifying water resources, both surface 

 and underground. 



(5) In determining routes, mileage, location of road-building material, 

 and topography in country traversed by public highways. 



(6) In classifying lands and in plotting the distribution and nature 

 of the soils. 



(7) As base maps for the plotting of information relating to the 

 geology and mineral resources of the country. 



Our first problem is therefore to gather reliable information as to 

 stream flow and topography. 



The Indiana Flood Commission, however, realizes that critical con- 

 ditions exist in several cities which can not wait the ten or twelve or 

 fifteen years required for the completion of such surveys. The commis- 

 sion has therefore made the best solution it can, and has studied all 

 available records, has computed rainfall and runoff, and determined to 

 the best of its ability, the amount of water which an Indiana city may 

 expect to take care of during future flood time. 



Briefly, the records of the heaviest storms in the Ohio Valley region 

 have been studied and the relation between the drainage area and the inches 

 of rainfall worked out for these storms. Several of these storms have been 

 studied, notably those of October, 1910 ; January, 1913, and February, 1884. 

 For instance, it was found that the center of the storm in January, 1914, 

 was over Southewestern Kentucky : the center of the storm of March, 1913, 

 was over a line from Mt. Carmel, 111., to Richmond, Ind. It is reasonable 

 to expect as a matter of chance, that similar storms in the future will be 

 centered fifty to one hundred miles from its former center. Cities must 

 therefore reasonably expect to take care of such storms. 



The result of the study is equivalent to fixing a future expected rain- 

 fall as equal to that of the storm of March, 1913, plus one-third additional 

 in the White River Valley, and one-fourth additional in the Wabash 

 watershed. Small drainage areas are yet to be studied. The river dis- 



