The hydrological regime of a forested tropical Andean catchment

The hydrology of tropical mountain catchments plays a central role in ecological function, geochemical and biogeochemical cycles, erosion and sediment production, and water supply in globally important environments. There have been few studies quantifying the seasonal and annual water budgets in the montane tropics, particularly in cloud forests. We investigated the water balance and hydrologic regime of the Kosñipata catchment (basin area: 164.4 km2) over the period 2010–2011. The catchment spans over 2500 m in elevation in the eastern Peruvian Andes and is dominated by tropical montane cloud forest with some high-elevation puna grasslands. Catchment-wide rainfall was 3112 ± 414 mm yr−1, calculated by calibrating Tropical Rainfall Measuring Mission (TRMM) 3B43 rainfall with rainfall data from nine meteorological stations in the catchment. Cloud water input to streamflow was 316 ± 116 mm yr−1 (9.2% of total inputs), calculated from an isotopic mixing model using deuterium excess (Dxs) and δD of waters. Field streamflow was measured in 2010 by recording height and calibrating to discharge. River run-off was estimated to be 2796 ± 126 mm yr−1. Actual evapotranspiration (AET) was 688 ± 138 mm yr−1, determined using the Priestley and Taylor–Jet Propulsion Laboratory (PT-JPL) model. The overall water budget was balanced within 1.6 ± 13.7%. Relationships between monthly rainfall and river run-off follow an anticlockwise hysteresis through the year, with a persistence of high run-off after the end of the wet season. The size of the soil and shallow groundwater reservoir is most likely insufficient to explain sustained dry-season flow. Thus, the observed hysteresis in rainfall–run-off relationships is best explained by sustained groundwater flow in the dry season, which is consistent with the water isotope results that suggest persistent wet-season sources to streamflow throughout the year. These results demonstrate the importance of transient groundwater storage in stabilising the annual hydrograph in this region of the Andes

An improved thermobalance reactor for the study of reduction and hydrofluorination of uranium feed materials /

Two thermobalances have been constructed which make use of an improved reactor design for the study of gas-solid reactions as they apply to the conversion of uranium oxide materiels to uranium tetrafluoride. Since temperature has been recognized as one of the most important rate-governing factors for both of the reactions involved in this transformation, the reactor design provides for maintaining the sample temperature constant to +- 1.0 deg C. at any selected temperature over the range 100 to 600 deg C. Rate-controlling variables such as reaction temperatures, gas flow rates, preheating time and bed depth have been studied in order to establish the ranges over which small variations in these factors can be ignored. (auth)."September 16, 1964"Includes bibliographic references (pages 42-44).Two thermobalances have been constructed which make use of an improved reactor design for the study of gas-solid reactions as they apply to the conversion of uranium oxide materiels to uranium tetrafluoride. Since temperature has been recognized as one of the most important rate-governing factors for both of the reactions involved in this transformation, the reactor design provides for maintaining the sample temperature constant to +- 1.0 deg C. at any selected temperature over the range 100 to 600 deg C. Rate-controlling variables such as reaction temperatures, gas flow rates, preheating time and bed depth have been studied in order to establish the ranges over which small variations in these factors can be ignored. (auth).Mode of access: Internet