Ecko hooked me up with a bunch of info, so I'm returning the favor by getting back to his (her?) question...
I figured maybe this might help some new desert dwellers, or perhaps veteran desert dwellers can expand on or correct the info. 
It might help with discussion on how to plan our various bugging bags.
For easier readability, I've moved my response to Ecko's other question into a new post. The prior post addresses
temperature changes, this post addresses various
environmental issues. I mentioned in my original post that I'd add more info. The comments from
my previous post are in italic, new comments are in regular text.
Ecko wrote:what sort of threats do you prepare for outside of climate which are based on your enviroment?
Essentially, all your basic needs are challenging: food, water, shelter. But we also have some strange benefits by living in the desert that I'll get to later. [now addressed throughout the comments below.]
LIGHT
The sun itself presents a challenge because the intensity means in some places you can badly burn in as little as 30min, even as early as 10am. You also burn more easily at higher elevation. Since there isn't much cloud cover here and trees are sparse at best, there's no natural protection from the sun. Which makes a hat and sunscreen essential for me when outside. I need a robe or long shirt for the mornings when camping (when I'm groggy and not paying attention to sun exposure).
It's not so much the heat here as an intensity of light.
As Molon Labe mentioned it's really a matter of direct sunlight. 95 degrees in the Northeast or Southeast feels worse than 105 in the desert due to the frequent breezes and lack of humidity in the desert. However the sunlight just seems significantly harsher, brighter and more direct here which is whole different kind of "hot".
The intensity of light and UV exposure has some downsides. As I mentioned you can burn more easily. It's also hell on anything rubber, drying it out and breaking it down much more quickly. Ditto for tarps and plastics. PVC pipe (such as used for shade structures or outdoor showers) usually doesn't last long before becoming brittle or cracking. It can weaken some fibers, such as cloth shade coverings or hammocks. These are all things to consider when choosing bugout gear or considering making longer term disaster structures.
However the intensity of light/UV exposure also offers some nifty benefits that other environments don't have.
We can easily do solar cooking most of the year via reflective material or dashboards. We can even bury cans in the sand during the day to heat up something like soup. We can use solar pasteurization to purify water (though additional purification may be needed depending on the water source). We can heat water for washing dishes and clothes or bathing just by leaving the water container in the sun in a dark container. Wet laundry dries in about 1 hour, even in the shade, Spring through Fall. Which is great if you need to pack up and go while bugging out, or even need frequent washings due to disaster conditions when bugging in. We can use also prime sun hours to kill bacteria on clothing or gear through UV exposure.
Those are all low-cost, low-effort, fuel-saving ways to provide food, water, and hygiene basics in a PAW environment that I consider unique to the desert.
And of course, we have official solar power through the use of solar panels. Few places allow the opportunity for year-round solar power. This can be used to recharge batteries when bugging out or actually power important items in the home when bugging in. Some backpacks even offer flexible solar panels attached so you can recharge your gear while hiking. That would be an excellent option for bugging out by foot or bike in the desert. I've been trying to figure out how to rig solar panels to a car roof for that same purpose.
The intensity of light and heat can also have an impact on how you choose to bugout and the timing of your plans.
While in other climates it's most advisable to travel by day and stay in at night for safety, the desert means it's sometimes safest to do the opposite.
The heat, heat-related exertion, increased risk of sunburn and minimal water resources can mean that it's best to lay low during most of the daylight hours and do most camp work or foot/bike traveling near sunrise/sundown, or even overnight. However, night travel by foot on open desert can mean you're more susceptible to biting/stinging creatures because there are many nocturnal creatures in the desert due to those same reasons.
As roscoe mentioned, a bugout by foot in the desert really isn't the best option. It requires thorough knowledge and experience with desert travel and survival, such as obtaining water, treating snakebites, making shelter. By car seems the best option, with the consideration that you may need to do some distances by bike or foot in an emergency. That's going to affect what kinds of items are stored in a BOB or car kit.
WATER
My observation has been that water takes on a Dune-like importance and magic in the desert. It's universally understood that you can die here from lack of water, even doing everyday things. It definitely amplifies your bugging danger when you're in an environment where not only do you require more water than average and burn through it more quickly, but it's in scarce natural supply. You can also go from drought-like conditions to dangerous flash floods in a matter of days or hours.
The most obvious challenge here is that natural water sources are rare outside of the mountains, particularly during the dry seasons. Some of the larger lake areas are also on Reservations, which makes the area off limits to any non-residents in many places. There are tricks to getting water such as dew collection and digging near plant life and in washes. But these are more a get-you-through water source, nothing abundant enough that you could consistently live off of.
This poses a special challenge for desert dwellers when planning their bugouts and BOB/GHB.
In addition to finding a water source, there's the challenge of water weight. Water is very heavy (I think it's 2.25lbs per 1L, 8lbs per 1gal) and being able to carry enough for even 2-3 days is just unrealistic for most people by foot. Many of us struggle with planning where to refill on water for a bugout, whether by car or by foot because you can be sure that everyone else will be hitting those same resources.
Another challenge is that the intense heat and sunlight mean you require more water than average.
Even storing an adequate amount at home can be difficult if you don't have a large house. For example, I need to store 14 gallons of water
bare minimum for 2 people for 1 week of bugging in. That gives us only 1 gallon each for drinking, washing and cooking, which would require strict emergency rationing. Realistically, I'd need at least twice that amount for any level of activity, particularly if cooling the residence without electricity were required. So now we're at 28 gallons (224lbs) for 2 people for 1 week. Storing a month's worth of water is very difficult in terms of both space and weight. And then all that water needs to be dumped and replenished on a 6 month cycle. And all of that is for a home bugin. Even if you had the room in your vehicle for that much water the increase in weight is going to negatively affect gas mileage, breaking and maneuverability.
One of the other dangers is that sweat evaporates very quickly, to the point that usually you're not aware you've been sweating. You shower at the beginning of the day and then wonder why you're clammy and stinky at the end of the day.
This means that you can very easily dehydrate without realizing it. So not only is water hard to find, not only do you require more of it than in most locations, but also you lose it more quickly and without knowing it.
The lack of humidity and rainfall can also be a major bonus.
For example, mildew and rust are almost non-issues here. Which means things like sleeping bags and tents can be stored outside without getting ruined and metal items last longer. (Though I've noticed that if any gear does get damp from dew or water it has to be thoroughly and promptly dried before it's put away or the heat will quickly cause mildew.) Also, the rapid evaporation of water means your gear can be ready to go shortly after washing or being caught in the rain.
CRITTERS
Most of the poisonous things that sting or bite you seem to live in the desert.
And many of them like to crawl into dark cool places during the day, then dark warm places at night -- like your shoes, or your gear, or places you'd naturally want to put your hands. There are a relatively large number of poisonous spiders and snakes, plus scorpions and a few poisonous lizards. While the likelihood of encountering these critters is low in the city areas, once you get to open desert the chances increase. For example
This means that desert folk need to keep specialty items like a snake bite kit in their FAK, know where local hospitals are that carry anti-venom for things such as rattlesnake bites, and/or have knowledge of how to treat various venomous bites and stings.
On the upside, the number of other bugs and critters is really low compared to most areas. Because really, not much can live here and there isn't much vegetation for them to survive on. This means even during monsoon season the mosquitos aren't too bad and we don't have to deal with things like ticks.
LANDSCAPE
The lack of real trees makes it hard to provide shade for yourself.
You can't string up a tarp or hammock to a cactus.
Generally the trees are not only too low to be helpful, but also way too far apart. Not to mention many of the trees are prickly and more bush-like. This means that most of the tarp tent constructions won't work in the desert, which in turn affects the shelter you pack in your BOB. The easiest one I've seen that works for deserts is
this simple tarp construction which requires just a hiking pole and some stakes.
The sparseness of vegetation also means there's very little in the way of edible plants compared to some areas.
However, there are some kinds of cactus that can be eaten and many cactus yield edible fruit around monsoon season. There also isn't much in the way of game. Near the foot hills and low mountain areas there are rabbit, coyotes, javelinas and pheasant. But these don't exist in abundance relative to a PAW situation.
In general though there isn't much in the natural landscape to be used as a reliable and consistent food source, which means you either need to bring your own food when bugging out or you better have expert desert survival skills.
The dirt here is loose and sandy, particularly in open desert. This means it's easily kicked airborne with wind.
I consider googles and a dustmask essential as part of a desert bag. Even along the highways you get anything from small dust devils (mini twisters that rip across the ground and quickly die out) to full dust wall fronts that sweep across the area and engulf the roads in a complete whiteout. Even in lower winds the dust in open desert kicks around enough to sting your eyes and irritate your throat.
Depending on the area, the dust can also do a number on your sinuses ("dust boogers"). A friend refers to the constant desert dust as "natural exfoliator".
It can irritate and dry out your exposed skin, which makes some kind of hearty moisturizer important for a BOB (I prefer shea butter because it heals as well as moisturizes). In heavier winds or storms it can act like sandpaper turning a sunburn into a painful sunburn + windburn + dustburn combo (ask me how I know this
).
Again, I think these are issues unique to the desert environment when making your PAW plans and gear.
WEATHER BENEFITS
As an upside to all the extreme weather issues, we are lucky enough to be able to plan on good clear weather for the majority of the year, nearly every day. That makes a big difference when you need to travel by foot, plan for shelter, or utilize natural power such as solar or wind. It also means that the climate is easier to deal with year round than other areas which may have very harsh winters and very humid summers.
We can also use simpler cooling methods such as evaporative coolers ("swamp coolers"). Sometimes simply shading openings or using reflective materials can greatly reduce the temperature of a structure. These are handy options should power be an issue or you find you have to bugin for an extended time.
Forgot about doing that.
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