“How can we create freshwater reservoirs over ocean water?”
Freshwater reservoirs are some of the most critical pieces of infrastructure for people. However, they can take up large areas of land. But what if we were to construct it on ocean water? Well, we can use physical barriers to create a boundary around the mouth of a river and allow freshwater to pour to make a Coastal Freshwater Reservoir. When there is a heavy rainstorm or too much water from the river, the flood gates open to let water out into the ocean. Coastal freshwater reservoirs can free up land space that otherwise would have been used by a land-based system. Examples of coastal freshwater reservoirs include Marina Barrage in Singapore (pictured) and Plover Cove in Hong Kong.
Soil is the base support for all types of physical structures and loads. When more shear stress is applied than the soil’s shear strength, the soil will undergo Soil Failure and slide. Soil failure can lead to structural collapse, such as in the floodwall sliding during Hurricane Katrina.
“How can we measure soil’s resistance to sliding from an applied force?”
Soil is literally the foundation of human civilization. From nurturing the plants we grow to supporting the buildings we live in, soil is a critical factor. One of the most important aspects of soil is its ability to resist sliding from an applied force, also called the Soil Shear Strength. Soil shear strength comes from the friction of its interlocking cohesive particles and its internal weight. Soils need to have a strong enough shear strength to support heavy structures.
“How can we quantify how easily water can pass through soil?”
Water can pass through soil through its pores and voids. Soil Permeability, or the ease with which water can move through soil, depends on the soil’s particle size, void ratio, soil structure, and more. Soil permeability is represented by the constant k and is in units of distance per time unit.
“What are the benefits and drawbacks of flat roofs?”
Flat roofs sit on top of buildings around the world. They offer simple, affordable construction and can serve as a space for people to gather. Flat roofs also make it easier to grow vegetation and install solar panels. However, their (nearly) flat design make it easy for water to pool and snow to pile on, resulting in structural damage. Because of the Benefits and Drawbacks of Flat Roofs, flat roofs are better suited for warm, dry climates like Egypt or inland California.
“How can we quantify how well soil particles resist shear failure?”
Soil particle bodies will collapse and fail when there’s a large enough shear stress applied to them. But how can we quantify this? Well, what if we were to take the soil body, place it on a theoretical inclined plane, and tilt the platform until the soil body collapses? The angle at which the body collapses is known as the Internal Friction Angle of Soil, and is the most widely used way to measure how well soil particles resist shear failure. The internal friction angle of soil is governed by the equation internal friction angle of soil = tan((shear stress due to friction)/(normal stress acting on soil))^-1. The higher the normal stress on the soil, the more it can resist shear stresses.
Building descriptions should be accurate to their name. But flat roofs completely buck this trend. Flat roofs typically have a small degree of slope (typically ten degrees of less) to allow water to runoff the roof to avoid pooling. This is Why Flat Roofs Are Not Actually Flat.
“How can we create large construction-ready sites for giant projects?”
Large construction projects such as new factories or data centers need voluminous amounts of land and infrastructure to support it. Gathering these piecemeal can lead to unbelievable cost overruns and bureaucratic delays. However, developers can purchase Megasites, large contiguous tracts of land that are construction-ready with infrastructure and close to transportation hubs support to remedy this. Megasites commonly complete environmental review ahead of time to ensure policy compliance.
“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.
Isaac's Science Blog 