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Chapter 7: Human Alterations to Riparian Areas
Common Agriculture
- Nationwide, agriculture has been responsible for the greatest decline in riparian area quantity and quality.
- Riparian areas, especially in the lowlands, have very fertile soils that are ideal for agriculture and typically close to water that is needed for irrigation.
- Converting riparian areas to agricultural crops changes the vegetation.
- In natural settings, riparian vegetation will protect soils from rain splash, overland flow, and stream bank erosion.
- Typically the crops planted for agricultural purposes are not as efficient in protecting the soil while also covering the soil only part of the year.
- Heavy machinery used for tilling in agricultural fields compacts soils.
- Compacted soils have decreased infiltration rates, increased overland flow, and sediment production that leads to more frequent and higher peak flows and subsequent flooding downstream.
- Increased stream flows may increase stream incision and bank erosion.
- Although more frequent and higher peak flows occur, at the same time base flow decreases, with many perennial streams becoming intermittent or ephemeral.
- In Arizona common agriculture impacts riparian areas because of the necessary irrigation that leads to significant water withdrawals from streams.
- Agriculture in Arizona uses 68% of the state’s water resources although it occupies 14% of the state's land.
- Agriculture in Arizona uses 68% of the state’s water resources although it occupies 14% of the state's land.
Figure 7.12. Agricultural crops use substantial amounts of water in Arizona.
- Some BMP’s for common agriculture include: riparian forest buffers, grass filters, terraces, no till farming, strip cropping, grassed waterways, more efficient irrigation methods (drip irrigation) that use less water, etc.
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