Aerial Salinity Mapping Systems

Sodium is an essential mineral involved in the function of our bodies and taste of our food. However, excess salt concentrations in soil can result in detrimental e�ects on plant growth, infrastructure, water quality, and land stability. A combination of natural oc-currences and man-made environmental e�ects coincide to create accumulation of salts beyond sustainable levels.

In the San Joaquin Valley, the “Breadbasket of the World,” concerns over soil salinity have become more prevalent, as data has shown a consistent increase over the past few decades. The soil salinity problem constitutes a paramount threat to the economic pros-perity of the San Joaquin Valley. For California to e�ciently and e�ectively take actions to combat this growing problem, we must �rst have a clear picture of the problem. Reliable sensor data is needed to prioritize critical regions and choose appropriate steps for remedi-ation. Existing measurement techniques are hazardous, expensive and time consuming, costing in the range of USD $100,000-130,000 per a 20 km^2 survey. In order to combat this issue, a more viable mapping systems needs to be developed

Aerial Salinity Mapping Systems (ASMS) has begun developing a solution that combines the long range and automated capabilities of Unmanned Aerial Vehicles with existing airborne electromagnetic tech-nology (AEM), optimizing time and money contraints required to obtain the necessary data. Through the use of an elentronically propelled autonomous airship design, we beleive we can develop a safer, more a�ordable, and most importantly sustain-able method for mapping out the San Joaquin Valley’s salinity levels. The bene�ts of an autonomous airship system:

• Long flight times for larger survey range

• Reduced fuel costs and energy consumption

• Simplistic design for minimal maintenance

• Remote sensing through autonomous control • More accurate flight paths for higher resolution map-ping

SJV SOIL SALINITY PROJECTSean Butler, Kevin Cramp, Chris Nicholls, Rudolfo Cruz

System Design

Results Conclusion & Recommendations

ABSTRACT: The San Joaquin Valley produces over 250 unique crops while grossing an annual value of more than $25 billion. ¬Soil salinity is a major issue in the preservation of the San Joaquin Valley’s fertility, costing the Department of Water Resources $15,000/mi2 just to map out the problematic sites. With an area of approximately 225,000 mi2, the total con-tracted price soars astronomically. Using ASMS Unmanned Aerial Systems (UAS), the price drops signi�cantly to a mere $35,000 capital cost without including the charging cost. As-suming harsh winds of around 10 miles/hour, the ASMS system takes signi�cantly longer than a contracted system, as the net forward speed is only approximately 2 miles/hour. With this information in mind, we concluded that the best course of action is to have a custom built set of ducted fans with higher thrust and lower power drain or to switch to a fossil fuel powered system.

Christopher NichollsField EngineerP: 925-775-5002E: cnicholls@ucmerced.edu

Rudolfo CruzField EngineerP: 559-339-8009E: rcruz3@ucmerced.edu

Thanks to:

The Problem:

Sean ButlerProject LeadP: 760-484-8533E: sbutler2@ucmerced.edu

Kevin CrampChief Financial O�cerP: 858-776-9799 E: kcramp@ucmerced.edu

• Airborne Electromagentic technology(AEM)

• Pulses electric current, which induces a magnetic field that concurrently induc-es a secondary electric �eld in the soil, which is then measured through a mag-netic receiver.

• The higher the salt concentration, the higher the conductivity.

• Measured data points input into proprietary software to create 2D/3D salinity maps

Airborne Electromagnetic MappingASMS Solution:

The images above illustrate the current AEM methods combined with an open-source data interpretation system used to generate maps.

The �gure above illustrates the overal function of the designed system.

The control system was designed to be autonomous with an option for manual override. The total system is comprised of a paparaz-zi-based Lisa-M v2 with an onboard IMU, several sensor and telemetry inputs, and eight control inputs.The figures below are a flow diagram of the control system and Paparazzi’s LisaM autopilot system used on the prototype.

The prototype demonstrated the control system to be a success in extremely low wind conditions, however in real-world situations the wind speeds tends to be random and impulsive. According to our �nal system design speci�cations, the full-scale system would spend signi�cantly more time than the contracted system. With an average speed of 2 mile/hour in heavy wind, the system collects data about as fast as a walking human operator. With these results in mind, there are several options to consider:

1. If time is not a requirement, the �nal system design will map out the San Joaquin Valley for a frac-tion of the cost of a contracted system. However, the time it will take to map the entire valley will not be environmentally viable. 2. If time is a requirement, the �nal system design will need to have the propulsion system replaced with a fossil-fuel power source and larger turbines. This will cut down the system’s time signi�cantly while reducing safety and environmental viability. 3. An electric ducted fan can be designed with higher thrust, signi�cantly lower power drain, and a renewable charging system, essentially making the system extremely viable environmentally and eco-nomically.

In conclusion, the unmanned aerial system is de�nitely viable with some further tweaking; howev-er the technology (in its current state) is not quite available to the general public.

Upon testing the autopilot system the following results were found: • The UAV able was able to maintain control in wind conditions of up to 3mph headwind. • The system was highly susceptible to losing course in strong gusts • Proved ablility to maintain stability in cross winds of 2 mph • System’s GPS is accurate to 10 –15 ft • Telemetry system needs improvement, maximum range was aproximately 600ft • Flight time was approximately 15 minutes with a 1000mAH battery

Contacts:UC Merced School of EngineeringStakeholders: Dean Dan Hirleman, Nara Narahari, Dr. Yangquan Chen, Brandon Stark, Bob RiceDWR: Jose Faria, Ken Johnson, Joe Tapia

As the curve shows, helium lift increases at an exponential rate. The only commercially available sensor that met the project speci�ca-tions had a weight of 22 pounds, which severely limited the choice of blimp size to a minimum of an approximately 22 foot diameter. With the negligible weight of the navigation system (1.55 pounds), the diameter selection was driven by the propulsion system and battery (totaling 33 pounds). Unfortunately, as the lift increases exponentially, so does the cost of the blimp. With our projected costs, the floatation system ac-counts for a mere 35% of the projected costs.