Open Water Ponds Research Articles

Evaluation of wetland creation and waterfowl use in conjunction with Abandoned Mine Lands in northeast Wyoming

During 1991 and 1992, we studied 92 wetlands, including open water (ponds) and emergent communities, created as a result of Wyoming Abandoned Mine Lands’ (AML) reclamation efforts in northeast Wyoming. Through these activities, over 300 wetlands were filled, reclaimed, created, or otherwise modified. For mitigation purposes, wetlands to be filled or modified were first evaluated using a Wetland Habitat Value (WHV) Model. Using the model, wetland losses were mitigated by increasing the WHV of some wetlands or by creating new wetlands elsewhere. We evaluated model performance in offsetting wetland loss and how well the model predicted waterfowl use. We also compared post-reclamation wetland sizes to those predicted by engineering plans and submitted for Section 404 permit approval. In our study, predicted WHVs were overestimated at 100% of the wetlands for which pre-reclamation WHVs were available (n=8). The most commonly overestimated variables were size, fraction of emergent cover, adjacent upland cover, and the number of bays and peninsulas. We obtained pre-construction size estimates for 64 of the original 80 wetlands. Fifty-five of 64 wetlands were smaller than pre-reclamation engineering goals. The WHV Model accurately predicted use of wetlands by migrating and breeding Canada geese (Branta canadensis), migrating dabbling ducks, and migrating diving ducks. Future users of the model must be careful not to overestimate results of planned mitigation efforts. Predicted size of constructed wetlands may be commonly overestimated; this possibility should be considered in mitigation plans, especially those involving wetland destruction.

Solar thermal modelling of a building with a roof pond and ventilation control systems

The paper proposes and presents thermal modelling of a ventilation-controlled, non-air-conditioned building with evaporative cooling (e.g. open water pond) over the roof for passive solar air conditioning. The ventilation rate, expressed in terms of number of air changes per hour, is assumed to be time-dependent, as should be the case in normal practice. A self-consistent periodic heat transfer analysis for a non-air-conditioned building with roof cooling and ventilation control systems, furnishing (assumed isothermal mass), windows, door and basement ground heat storage effects has been developed to assess the feasibility of the proposed passive space air-conditioning. It is shown that for no-ventilation summer nights the inside air temperature remains higher than the ambient air temperature even with an effective roof cooling system, and hence the windows should be opened to lose the internal heat and to introduce cool and fresh outside air. It is found that for a ventilation-controlled building with a roof pond the passive solar air conditioning can be achieved more effectively.

Periodic theory of an open roof pond

This paper describes an analysis of the reduction of the heat flux coming into a room through a roof with an open water pond. A periodic analysis of the system, based on the linearisation of Dunkle's 6 expressions for convective, radiative and evaporative losses, is presented. Numerical computation for the heat flux has been carried out for a typical hot day, the 19th of June, 1979, in New Delhi. These results were compared with those for a water-sprayed system. It was found that, for typical parameters, there are reductions in the maximum heat flux entering the room of 48% and 41% for the roof pond and water-sprayed systems, respectively (for a relative humidity of 0·8). The corresponding reductions in daily heat input into the room are 20% and 35%, respectively. Load levelling is, of course, much better in the case of the open roof pond.