T iled Acreages within Physiographic Positions 



A much greater acreage of tile has been Installed In recent 

 alluvial fans than in older fans, basin rim, or basin 

 positions. The acreages shown in Table 1 represent all the 

 tile systems installed up to I969 within the Valley from 

 Tracy to south of Bakersfield, including a few tile systems 

 on the east side of the Valley, These acreages were deter- 

 mined from scaled drawings on U . S, Geological Survey 

 quadrangle sheets, 7-l/2-minute series. Acreages are 

 estimates based on the actual areal coverage of tbe tile 

 laterals. Interceptor drains were allowed 40 acres for each 

 one-fourth mile of conduit, when isolated from other tile 

 systems , 



TABLE 1 



TILE ACREAGES WITHIN MAJOR PHYSIOGRAPHIC POSITIONS 

 OF THE SAN JOAQUIN VALLEY FLOOR 

 1968 



Physiographic Position j Tiled Acreage 



Recent alluvial fan 17,078 



Older alluvial fan 7,8^0 



Basin rim 6,559 



Basin 2,221 



Total 33,698 



Soils and Soil Characteristics 



Soil characteristics are one of the most important factors 

 which determine the quantity and quality of drainage in tile 

 systems. A thorough picture of soil morphology and genesis 

 is necessary to understand the variable soil conditions that 

 exist along the west side. 



M orphology and Genesis 



The west side of the San Joaquin Valley, as referred to in 

 this report, refers to the vast expanse of soils on the 

 eastern slope of the Diablo Range. This area extends from 

 Tracy to south of Bakersfield. Physiography of this area 

 consists of gently sloping and coalescing alluvial fans that 

 extend from the base of the mountains to a "salt rim" zone 



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