Examining the Contributions of Glacial Till Water to Storm Runoff using Two- and Three-Component Hydrograph Separations

Two- and three-component hydrograph separations based on 18O and dissolved silica are used to investigate the contributions of glacial till water to the storm runoff of a headwater stream on the Canadian Shield. Two-component isotopic hydrograph separations based on 18O indicate that the volume and flux of event water could be accounted for by direct precipitation onto saturated areas. Three-component hydrograph separations distinguish between event water, preevent soil water, and preevent till water. These results show that groundwater flow through coarse-textured glacial tills can make a significant contribution to stream discharge during runoff events (29 and 62% in this study) despite the lower hydraulic conductivities of the tills compared to the overlying soils. The three-component hydrograph separations also demonstrate that the relative contributions of preevent soil water and preevent till water changed during one runoff event such that the average water chemistry of the preevent component varied during the event. Two-component hydrograph separations using dissolved silica indicate that seasonal changes in the till water contributions also occur and are related to groundwater levels. Measurements of vertical hydraulic gradients during runoff events indicate that the increase in flow from the tills to the soils is minimal and cannot account for the large and rapid increase in till water flow into the stream. Till water that has discharged to the soils prior to the event is probably being flushed from the soils into the stream during events

Intelligence as inference or forcing Occam on the world

We propose to perform the optimization task of Universal Artificial Intelligence (UAI) through learning a reference machine on which good programs are short. Further, we also acknowledge that the choice of reference machine that the UAI objective is based on is arbitrary and, therefore, we learn a suitable machine for the environment we are in. This is based on viewing Occam’s razor as an imperative instead of as a proposition about the world. Since this principle cannot be true for all reference machines, we need to find a machine that makes the principle true. We both want good policies and the environment to have short implementations on the machine. Such a machine is learnt iteratively through a procedure that generalizes the principle underlying the Expectation-Maximization algorithm

Probabilistic model checking multi-agent behaviors in dispersion games using counter abstraction

Accurate analysis of the stochastic dynamics of multi-agent system is important but challenging. Probabilistic model checking, a formal technique for analysing a system which exhibits stochastic behaviors, can be a natural solution to analyse multi-agent systems. In this paper, we investigate this problem in the context of dispersion games focusing on two strategies: basic simple strategy (BSS) and extended simple strategies (ESS). We model the system using discrete-time Markov chain (DTMC) and reduce the state space of the models by applying counter abstraction technique. Two important properties of the system are considered: convergence and convergence rate. We show that these kinds of properties can be automatically analysed and verified using probabilistic model checking techniques. Better understanding of the dynamics of the strategies can be obtained compared with empirical evaluations in previous work. Through the analysis, we are able to demonstrate that probabilistic model checking technique is applicable, and indeed useful for automatic analysis and verification of multi-agent dynamics.No Full Tex

The First VERITAS Telescope

The first atmospheric Cherenkov telescope of VERITAS (the Very Energetic Radiation Imaging Telescope Array System) has been in operation since February 2005. We present here a technical description of the instrument and a summary of its performance. The calibration methods are described, along with the results of Monte Carlo simulations of the telescope and comparisons between real and simulated data. The analysis of TeV $\gamma$-ray observations of the Crab Nebula, including the reconstructed energy spectrum, is shown to give results consistent with earlier measurements. The telescope is operating as expected and has met or exceeded all design specifications.Comment: Accepted by Astroparticle Physic

Hydrogeology and Groundwater Quality Atlas of Malawi : Water Resource Area 10: The South East Lakeshore Catchment

Groundwater in Water Resource Area 10 is interpreted within the same context as presented in the Hydrogeology and Water Quality Atlas Bulletin publication. A general description of the Hydrogeology of Malawi and its various units is provided here to remind the reader of the complexity of groundwater in Malawi and its nomenclature. The various basement geologic units have variable mineralogy, chemistry, and structural history that may be locally important for water quality parameters such as Fluoride, Arsenic and geochemical evolution. Therefore, translation of geologic units to potential hydrostratigraphic units was based on the 1:250,000-scale Geological Map of Malawi compiled by the Geological Survey Department of Malawi (Canon, 1978). Geological units were grouped into three main aquifer groups for simplicity

Hydrogeology and Groundwater Quality Atlas of Malawi : Water Resource Area 6: The Dwangwa River Catchment

Groundwater in Water Resource Area 6 is interpreted within the same context as presented in the Hydrogeology and Water Quality Atlas Bulletin publication. A general description of the Hydrogeology of Malawi and its various units is provided here to remind the reader of the complexity of groundwater in Malawi and its nomenclature. The various basement geologic units have variable mineralogy, chemistry, and structural history that may be locally important for water quality parameters such as Fluoride, Arsenic and geochemical evolution. Therefore, translation of geologic units to potential hydrostratigraphic units was based on the 1:250,000-scale Geological Map of Malawi compiled by the Geological Survey Department of Malawi (Canon, 1978). Geological units were grouped into three main aquifer groups for simplicity

Hydrogeology and Groundwater Quality Atlas of Malawi : Water Resource Area 11: The Lake Chiuta Catchment

Groundwater in Water Resource Area 11 is interpreted within the same context as presented in the Hydrogeology and Water Quality Atlas Bulletin publication. A general description of the Hydrogeology of Malawi and its various units is provided here to remind the reader of the complexity of groundwater in Malawi and its nomenclature. The various basement geologic units have variable mineralogy, chemistry, and structural history that may be locally important for water quality parameters such as Fluoride, Arsenic and geochemical evolution. Therefore, translation of geologic units to potential hydrostratigraphic units was based on the 1:250,000-scale Geological Map of Malawi compiled by the Geological Survey Department of Malawi (Canon, 1978). Geological units were grouped into three main aquifer groups for simplicity

Hydrogeology and Groundwater Quality Atlas of Malawi : Water Resource Area 7: The South Rukuru and North Rumphi River Catchment

Groundwater in Water Resource Area 7 is interpreted within the same context as presented in the Hydrogeology and Water Quality Atlas Bulletin publication. A general description of the Hydrogeology of Malawi and its various units is provided here to remind the reader of the complexity of groundwater in Malawi and its nomenclature. The various basement geologic units have variable mineralogy, chemistry, and structural history that may be locally important for water quality parameters such as Fluoride, Arsenic and geochemical evolution. Therefore, translation of geologic units to potential hydrostratigraphic units was based on the 1:250,000-scale Geological Map of Malawi compiled by the Geological Survey Department of Malawi (Canon, 1978). Geological units were grouped into three main aquifer groups for simplicity

Hydrogeology and Groundwater Quality Atlas of Malawi : Bulletin

Malawi’s water scarcity index is climbing and contrary to popular belief, Malawi is not a water rich nation. Given Lake Malawi holds 7,750 km3 of water, it dominates water resource management perceptions, however Lake level variation is ultimately limited between 471.5 and 477masl, and in 2022 ranged from 474 to 475.25masl, resulting in an annual renewable freshwater input of 35.9 km3. The estimates of annual recharge to Groundwater (<100m depth) in Malawi are conservatively estimated to range between 1.0 km3 and 7.7 km3 with a total Groundwater volume of between 96.7 km3 and 1,108 km3, with an average age of between 95 and 140 years. Groundwater is thus the largest distributed available freshwater resource in Malawi, but as with Lake Malawi, one that is dependent on annual recharge. Groundwater is also vital for sustained river flow in Malawi, it is the key water resource that has potential to provide adaptation and resilience to development challenges and climate change if managed properly. The Government of Malawi is committed to “provide adequate, reliable, and sustainable water and sanitation services to the people of Malawi to meet the ever-increasing demand for safe water for domestic, institutional, commercial, and agricultural use, with emphasis on the poor and rural communities”. Although groundwater is a reliable resource when properly managed, the lack of professional oversight and limited information reaching planners, decision-makers and users commonly results in it being used as a second option to more expensive surface water schemes. Limited capacity results in a lack of proper and professional hydrogeological interventions, which has led to a 39.4% failure rate (16% non-functional, 23.4% partially functional) for rural single point groundwater water supplies. The Ministry is the National Water Policy holder, and has in place detailed guidance and standard operating procedures for the development, use and monitoring of Malawi’s groundwater resources. There is a push to expand groundwater abstraction using ‘solar’ or ‘reticulated’ groundwater sources, and these investments must be implemented by professional hydrogeologists who gather and use site specific data to determine sustainable groundwater yields, limiting risks of wide-spread failure and over-abstraction of limited groundwater resources. Accordingly, all groundwater abstraction points must be vetted by the National Water Resources Authority (NWRA) and, were required, assigned abstraction permits that maintain groundwater resources for the environment (rivers/wetlands), industry, and agricultural uses