As more and more arid and dry land areas are transformed into wasteland and pollution source areas due to changing climatic conditions the study of windblown erosion has become an ever increasing interest. The need for field sensors to monitor and evaluate this encroaching problem has not only escalated but become more demanding for diversity in erosion sensor capability. This project examines an opportunity for erosion researchers to acquire a new windblown erosion sensor that can provide enhanced measurement capabilities above all existing saltation sensors including active dune measurement capability. The new sensor type also solves many problems inherent to existing sensor configurations by providing a completely unobtrusive omni-directional sensor that also does not exhibit asymmetrical response problems. OBJECTIVES: Development of this sensor presents a new tool for erosion related researchers. It is anticipated that it will be as successful as the earlier vertical erosion sensor and further support new theoretical wind erosion prediction schemes such as erosion seconds as proposed by Dr. John Stout (USDA-ARS Lubbock, Texas). We expect this feasibility study for the new sensor will not only produce a rugged low cost erosion sensor but may also produce a closely related low cost rain impact sensor, also in demand by water erosion and biological spore dispersion communities. Primary objectives are to produce evidence through laboratory and field tests demonstrating the ability and effectiveness of the new flat plate erosion sensor design. The intent of this new flat plat design is to eliminate undesirable effects of scouring around the base of vertically oriented sensor shapes. Also to create a new tool for dune migration studies by creating a non-obtrusive sensor that literally floats on an active dune surface. Secondary on the agenda is to establish a universal sensor response specification. Establishing a set of specifications for all saltation sensors such as minimum discernable signal (MDS) and dynamic range allows direct comparison between all electronic saltation sensors produces. This in turn makes available a process for a principal investigator to make an intelligent selection decision when preparing for a particular study. It also provides an investigator with a baseline reference for his/her subsequent data reports and resulting publications. The primary objectives focus on demonstrating the ability of this new flat plate design to provide erosion researchers with a particle sensing saltation sensor superior in many ways to existing sensor designs. However, it is not the intent of this new design to replace existing vertically oriented saltation sensors as they have ability to respond to saltating particles at selectable heights above the ground whereas the proposed sensor is targeting total saltation activity. Laboratory wind tunnel and actual field testing of this sensor will be performed and correlated. APPROACH: The feasibility approach for determination of the newly proposed sensor's ability to produce usable saltation data and demonstrate advantages over existing vertical sensor designs involves two comparative studies. One study will quantify the sensors response under the controlled and stable conditions of a laboratory wind tunnel. The other study will provide sensor response to saltating activity under actual field and dune saltation conditions. 1) Laboratory wind tunnel testing; An economical laboratory wind tunnel will be constructed to facilitate simulation of natural saltation activity using glass spheres as the saltating medium. It will be very similar to the small wind tunnel produced by this company for NOAA (National Oceanic and Atmospheric Administration) in 1988 which successfully provided data for an extensive erosion study involving the effect of lateral coverage on an eroding surface. 2) Produce prototype sensors for testing. A minimum quantity of ten prototype sensors will be produced to use in the laboratory wind tunnel and for the field data comparison analysis. Five to be sent to USDA-ARS in Texas for field trails and five for an extensive wind tunnel study. 3) Wind tunnel testing will cover sensor response to determine minimum detectable particle activity and continue through a substantial range of wind speeds creating a response profile. Particle velocity and trajectory information will be determined via streak photography. Photographic observations will also help verify the new designs ability to thwart scouring activity. The wind tunnel data taken throughout this study will be used to formulate saltation sensor response specifications. These criteria will aid in establishing a protocol for saltation sensor response specifications. It is anticipated that more than one level of protocol/specifications may be presented. This is because we have found by past experience there two distinct several levels of expertise that can be associated with different users perception or ability to perceive the complex nature of the data produced by this type of sensor. Data considered usable for those involved in simple movement monitoring can be substantially less demanding that of research studying the physics of blowing sand. There is also a difference between an interest in particle energy and its associated mass flux and those interested in the determination of threshold velocities for a given surface. Also, we believe it is advantageous for all concerned to be able to relate data produced by various sensor manufacturers including performance between individual sensors of the same type and from the same source. 4) Field testing performed by USDA-ARS in Lubbock Texas will provide sensor response data of real world erosion activity and the new sensors shape ability to be an effective dune saltation sensor. 5) An interim report will provide progress toward these goals followed by a final report at the end of the project stating data, methods and accomplishments. If successful, an application for Phase II development toward a commercially available sensor of this type will be strongly considered.
