The Freshwater-Saltwater Interface

The Freshwater-Saltwater Interface

07/24/26

“What makes the interface between saltwater and freshwater so unique?”

Freshwater and saltwater have substantially different properties. When they meet in coastal aquifers, they form a Freshwater-Saltwater Interface. The freshwater-saltwater interface is a transition zone where freshwater “floats” as a layer above the zone of transition (which in turn “floats” above more pure saltwater) because of saltwater’s greater density. The further down you go in a coastal aquifer, the saltier the groundwater becomes. Coastal aquifer infrastructure operators must be careful with the freshwater-saltwater interface, because overpumping can lead to upconing of saltwater and result in saltwater intrusion.

Science Parks

Science Parks

07/23/26

“How can universities, governments, and private industries expand research by co-locating workplaces?”

Universities, governments, and private industries can drive scientific and technological innovation. Consequently, it’s a logical step for urban areas to carve out districts for these institutions to work close to each other. These so-called Science Parks facilitate research operations, technology transfer, and knowledge sharing among tenants. If designed well, science parks can superdrive scientific progress. Example science parks across the world include the UCSC Monterey Bay Education, Science & Technology Center, the Metrotech Center at New York University Tandon School of Engineering, Sophia Antipolis in Southeast France, and Saigon Hi-Tech Park in Ho Chi Minh City.

The Roadless Rule

The Roadless Rule

07/22/26

“What’s the U.S.federal rule that protects backcountry forests from road construction, why is it under attack, and what can you do to help?”

Remote, backcountry forests are marvelous pieces of geography. Not only do they nurture diverse ecosystems and regulate our planet’s carbon balance, but they also provide world-class recreational opportunities. In 2001, the U.S. federal government introduced The Roadless Rule, which protects roughly 60 million acres of American backcountry forests and grasslands from road and logging development. This rule has been an incredible success, sustaining not only the forests themselves but also drinking water access to over 25 million Americans. However, this is now all under threat as the USDA released a notice of intent to repeal the roadless rule, likely by (as of writing) late 2026. If you are a U.S. resident, you can fight to protect the roadless rule by calling your representatives, using the information found in the link here.

Force Main Discharge Elevation

Force Main Discharge Elevation

07/21/26

“How can we quantify the height a force main must pump to?”

Force mains pump wastewater to overcome elevational or frictional differences. The height they must pump to is called the Force Main Discharge Elevation. Wastewater does not need pumping to move once it reaches the force main discharge elevation since it will go downhill with gravity. The force main discharge elevation does not need to be above the pump inlet since the pump might be present to work against frictional losses only.

Force Mains

Force Mains

07/20/26

“What’s so special about pipes that carry wastewater using a pump?”

It’s typical for sewers to carry wastewater using gravity. However, sometimes the sewer needs to carry wastewater against gravity using pumps. Pipes that carry wastewater using pumps are called Force Mains. Force mains are typically filled due to pressurization.

Pump Curve Duty Point

Pump Curve Duty Point

07/19/26

“What are the settings at which a pump will operate when connected to a piping system?”

Pumps have their own pump curves that measure the correlation between flow and head, and piping systems have system curves that demonstrate their relation between head and required flow. The intersection point of these curves is called the Pump Curve Duty Point, and is the point at which pumps will operate.

Dirty Rain

Dirty Rain

07/18/26

“What happens when raindrops hit highly polluted air?”

Nearly everywhere on planet Earth experiences rain. Rain interacts with everything in the atmosphere, including any pollutants flying around. Raindrops can capture particulate matter such as ash, dust, and smoke. This takes the pollutants out of the atmosphere and onto the ground, where they create a dirty layer. This Dirty Rain acts similarly to a wet scrubber, and commonly occurs in highly polluted parts of the world. Transporting the particulate matter out of the atmosphere can temporarily increase air quality.

Dammed River Reservoirs

Dammed River Reservoirs

07/17/26

“How can we dam rivers to create reservoirs?”

People can create reservoirs to store water. One way is to install a dam over a river, bringing its flow to a near halt and practically turning the water body into a lake. These Dammed River Reservoirs can hold vast amounts of water throughout the year. Water is typically still let out through controlled release. Dams can release enough water to generate hydropower. Dammed river reservoirs can protect against floods by concentrating water upstream and releasing only a paltry amount downstream. Dammed river reservoirs can be environmentally catastrophic (especially for Indigenous livelihoods), and people may remove dams to restore the natural environment. Damned river reservoirs are also liable to sedimentation buildup and algae blooms from the stopped flow.

Reservoirs

Reservoirs

07/16/26

“How can we create giant reserves of water for later use?”

Water is one of the most fundamental components of human life. Consequentially, water needs to be stored for people to avoid catastrophe. Reservoirs are large water storage bodies to fill this need. Reservoirs can be natural (like lakes) or artificial (like dammed rivers). Reservoirs can also release water to assist drought-stricken communities.