This thesis describes in-situ flow tests on bentonite borehole plugs installed in granite, as well as laboratory experiments on similar plugs. Prior to sealing, the hydraulic conductivity of the boreholes is tested. These measurements, together with core logs and borehole videologs, permit the selection of suitable seal test intervals. Standard waterwell sealing bentonite products and emplacement procedures are used for borehole sealing. Transient (short-term) and steady-state (long-term) testing determines the sealing performance of the plugs (although the premature termination of the "steady state" testing precluded full data collection). Laboratory and field experiments confirm the great difficulty of obtaining accurate performance values for bentonite plugs as installed, due to the simultaneous saturation, swelling, and consolidation effects. Conventional installation of readily available seals can provide adequate borehole seals. Bentonite plugs of this type are heterogeneous and weak. Improved testing procedures and analyses are needed if actual conductivity values are to be obtained in a reasonable testing time.

The sediment rating curve (SRC) method was used to study the effects of vegetative manipulations on sediment concentrations on the Beaver Creek watersheds of north-central Arizona. A linear model was best in the analysis of streamflow-sediment relationships. The corrected linear model eliminated some bias of the linear model and improved prediction. Partitioning data by streamflow-generating events and hydrograph stages produced significantly different SRCs and increased the descriptive and predictive powers. Due to insufficient data at the high streamflow range, SRCs for the pinyon-juniper watersheds had low values of ra SRCs for the ponderosa pine watersheds produced better results. More overstory removal resulted in higher sediment concentrations.

The stability-corrected aerodynamic method was used to estimate fluxes of sensible and latent heat over an irrigated winter wheat field at Maricopa Agricultural Center in southern Arizona. These estimates were compared against the more precise Bowen ratio energy balance measurements made at the same location. The data were collected for 43 consecutive days over a range of canopy conditions. The aerodynamic method performed poorly against the validated Bowen ratio method at this site. Fluxes of latent heat were underestimated by the stability-corrected aerodynamic method. Sensible heat fluxes sometimes agreed well, but were often low. A new model was developed by combining AERO sensible heat (H(aero) with net radiation and soil heat flux to estimate latent energy as a residual (Le(resid)) in the surface energy balance equation. This aerodynamic energy balance (AEB) method, produced R² values of 0.97 and 0.78 for the wet and dry periods respectively.

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