CERP C-111 Spreader Canal Phase 1 Western Features Soil Water and Groundwater Monitoring

Soil water and groundwater monitoring support the development of soil water retention curves by the University of Florida Institute of Food and Agricultural Sciences (IFAS) [Contractor] and the correlation of soil moisture data to groundwater levels and canal stages. As part of adaptive water management practices associated with this Project, water level increases are planned to occur by modifying stage at the S-18C structure. The increases are to be incremental in nature by 0.1 ft per step with a total increase of potentially 0.4 ft. It is anticipated that this rise in canal water elevation will influence groundwater levels in adjacent areas. This phenomenon has been reported in research conducted by the University of Florida (Ritter and Muñoz-Carpena, 2006, Journal of Hydrology).

One of the areas affected by project operations is an active agricultural area with a unique geographic location at the foot of the coastal bench. It is considerably lower in land elevation than surrounding farm areas just to the north. Changes in the water table can impact roots of local crops causing reductions in crop yields or complete loss of crops. There is concern on how the planned rise in water elevation in the canal (due to change in operation of S-18C) will influence the usability of adjacent land for agricultural purposes. Currently, agriculture located in the adjacent land is primarily composed of vegetable and ornamental nursery crops. Vegetables are predominantly grown during the dry season while ornamental nursery crops are produced year round. Nursery crops may be containerized or may be planted in the field.

There are three (3) main concerns to address regarding the change in canal elevation:
1) Will the rise in canal water level change soil moisture so that the land is not suitable for current uses?
2) Will the rise in canal water level continue to provide adequate flood protection?
3) How much time should be allowed to lower the water table if a large rainfall event is expected?
Soil properties vary within this region, with three (3) dominant soil types: Biscayne gravelly marl, Krome very gravelly loam, and Chekika very gravelly loam. Determination of the soil water retention curve for each of these soils is critical to understanding their soil water holding capacity and drainage characteristics. The soil water retention curve provides a relationship between the soil suction or tension and the soil water volumetric content. The soil water retention curve is developed in the laboratory. This relationship is used to understand soil water dynamics in the field, where real-time soil moisture data at specific sites is collected using soil moisture sensors. The soil moisture data collected can then be correlated with measured groundwater level using hydrostatic assumptions and groundwater level data (Barquin et al., 2009; UF MS thesis). It is also possible to develop a relationship between groundwater level and canal level (Ritter and Muñoz-Carpena, 2006, Journal of Hydrology). The development of these hydrologic relationships depends on the collection and evaluation of quality, georeferenced soil moisture, groundwater level, and canal stage data.

The objectives of this Project are:

1) To collect soil water content and groundwater level data in three (3) dominant soil types in the affected agricultural area near the C-111 canal.
2) To evaluate collected data to determine if relationships can be developed between groundwater level, canal level and soil water content